ClickHouse/docs/en/whats-new/changelog/2019.md

---
toc_priority: 77
toc_title: '2019'
---

## ClickHouse Release 19.17 {#clickhouse-release-v19-17}

### ClickHouse Release 19.17.6.36, 2019-12-27 {#clickhouse-release-v19-17-6-36-2019-12-27}

#### Bug Fix {#bug-fix}

-   Fixed potential buffer overflow in decompress. Malicious user can pass fabricated compressed data that could cause read after buffer. This issue was found by Eldar Zaitov from Yandex information security team. [#8404](https://github.com/ClickHouse/ClickHouse/pull/8404) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed possible server crash (`std::terminate`) when the server cannot send or write data in JSON or XML format with values of String data type (that require UTF-8 validation) or when compressing result data with Brotli algorithm or in some other rare cases. [#8384](https://github.com/ClickHouse/ClickHouse/pull/8384) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed dictionaries with source from a clickhouse `VIEW`, now reading such dictionaries does not cause the error `There is no query`. [#8351](https://github.com/ClickHouse/ClickHouse/pull/8351) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed checking if a client host is allowed by host_regexp specified in users.xml. [#8241](https://github.com/ClickHouse/ClickHouse/pull/8241), [#8342](https://github.com/ClickHouse/ClickHouse/pull/8342) ([Vitaly Baranov](https://github.com/vitlibar))
-   `RENAME TABLE` for a distributed table now renames the folder containing inserted data before sending to shards. This fixes an issue with successive renames `tableA->tableB`, `tableC->tableA`. [#8306](https://github.com/ClickHouse/ClickHouse/pull/8306) ([tavplubix](https://github.com/tavplubix))
-   `range_hashed` external dictionaries created by DDL queries now allow ranges of arbitrary numeric types. [#8275](https://github.com/ClickHouse/ClickHouse/pull/8275) ([alesapin](https://github.com/alesapin))
-   Fixed `INSERT INTO table SELECT ... FROM mysql(...)` table function. [#8234](https://github.com/ClickHouse/ClickHouse/pull/8234) ([tavplubix](https://github.com/tavplubix))
-   Fixed segfault in `INSERT INTO TABLE FUNCTION file()` while inserting into a file which does not exist. Now in this case file would be created and then insert would be processed. [#8177](https://github.com/ClickHouse/ClickHouse/pull/8177) ([Olga Khvostikova](https://github.com/stavrolia))
-   Fixed bitmapAnd error when intersecting an aggregated bitmap and a scalar bitmap. [#8082](https://github.com/ClickHouse/ClickHouse/pull/8082) ([Yue Huang](https://github.com/moon03432))
-   Fixed segfault when `EXISTS` query was used without `TABLE` or `DICTIONARY` qualifier, just like `EXISTS t`. [#8213](https://github.com/ClickHouse/ClickHouse/pull/8213) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed return type for functions `rand` and `randConstant` in case of nullable argument. Now functions always return `UInt32` and never `Nullable(UInt32)`. [#8204](https://github.com/ClickHouse/ClickHouse/pull/8204) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed `DROP DICTIONARY IF EXISTS db.dict`, now it does not throw exception if `db` does not exist. [#8185](https://github.com/ClickHouse/ClickHouse/pull/8185) ([Vitaly Baranov](https://github.com/vitlibar))
-   If a table wasn’t completely dropped because of server crash, the server will try to restore and load it [#8176](https://github.com/ClickHouse/ClickHouse/pull/8176) ([tavplubix](https://github.com/tavplubix))
-   Fixed a trivial count query for a distributed table if there are more than two shard local table. [#8164](https://github.com/ClickHouse/ClickHouse/pull/8164) ([小路](https://github.com/nicelulu))
-   Fixed bug that lead to a data race in DB::BlockStreamProfileInfo::calculateRowsBeforeLimit() [#8143](https://github.com/ClickHouse/ClickHouse/pull/8143) ([Alexander Kazakov](https://github.com/Akazz))
-   Fixed `ALTER table MOVE part` executed immediately after merging the specified part, which could cause moving a part which the specified part merged into. Now it correctly moves the specified part. [#8104](https://github.com/ClickHouse/ClickHouse/pull/8104) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Expressions for dictionaries can be specified as strings now. This is useful for calculation of attributes while extracting data from non-ClickHouse sources because it allows to use non-ClickHouse syntax for those expressions. [#8098](https://github.com/ClickHouse/ClickHouse/pull/8098) ([alesapin](https://github.com/alesapin))
-   Fixed a very rare race in `clickhouse-copier` because of an overflow in ZXid. [#8088](https://github.com/ClickHouse/ClickHouse/pull/8088) ([Ding Xiang Fei](https://github.com/dingxiangfei2009))
-   Fixed the bug when after the query failed (due to “Too many simultaneous queries” for example) it would not read external tables info, and the
    next request would interpret this info as the beginning of the next query causing an error like `Unknown packet from client`. [#8084](https://github.com/ClickHouse/ClickHouse/pull/8084) ([Azat Khuzhin](https://github.com/azat))
-   Avoid null dereference after “Unknown packet X from server” [#8071](https://github.com/ClickHouse/ClickHouse/pull/8071) ([Azat Khuzhin](https://github.com/azat))
-   Restore support of all ICU locales, add the ability to apply collations for constant expressions and add language name to system.collations table. [#8051](https://github.com/ClickHouse/ClickHouse/pull/8051) ([alesapin](https://github.com/alesapin))
-   Number of streams for read from `StorageFile` and `StorageHDFS` is now limited, to avoid exceeding the memory limit. [#7981](https://github.com/ClickHouse/ClickHouse/pull/7981) ([alesapin](https://github.com/alesapin))
-   Fixed `CHECK TABLE` query for `*MergeTree` tables without key. [#7979](https://github.com/ClickHouse/ClickHouse/pull/7979) ([alesapin](https://github.com/alesapin))
-   Removed the mutation number from a part name in case there were no mutations. This removing improved the compatibility with older versions. [#8250](https://github.com/ClickHouse/ClickHouse/pull/8250) ([alesapin](https://github.com/alesapin))
-   Fixed the bug that mutations are skipped for some attached parts due to their data_version are larger than the table mutation version. [#7812](https://github.com/ClickHouse/ClickHouse/pull/7812) ([Zhichang Yu](https://github.com/yuzhichang))
-   Allow starting the server with redundant copies of parts after moving them to another device. [#7810](https://github.com/ClickHouse/ClickHouse/pull/7810) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fixed the error “Sizes of columns does not match” that might appear when using aggregate function columns. [#7790](https://github.com/ClickHouse/ClickHouse/pull/7790) ([Boris Granveaud](https://github.com/bgranvea))
-   Now an exception will be thrown in case of using WITH TIES alongside LIMIT BY. And now it’s possible to use TOP with LIMIT BY. [#7637](https://github.com/ClickHouse/ClickHouse/pull/7637) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov))
-   Fix dictionary reload if it has `invalidate_query`, which stopped updates and some exception on previous update tries. [#8029](https://github.com/ClickHouse/ClickHouse/pull/8029) ([alesapin](https://github.com/alesapin))

### ClickHouse Release 19.17.4.11, 2019-11-22 {#clickhouse-release-v19-17-4-11-2019-11-22}

#### Backward Incompatible Change {#backward-incompatible-change}

-   Using column instead of AST to store scalar subquery results for better performance. Setting `enable_scalar_subquery_optimization` was added in 19.17 and it was enabled by default. It leads to errors like [this](https://github.com/ClickHouse/ClickHouse/issues/7851) during upgrade to 19.17.2 or 19.17.3 from previous versions. This setting was disabled by default in 19.17.4, to make possible upgrading from 19.16 and older versions without errors. [#7392](https://github.com/ClickHouse/ClickHouse/pull/7392) ([Amos Bird](https://github.com/amosbird))

#### New Feature {#new-feature}

-   Add the ability to create dictionaries with DDL queries. [#7360](https://github.com/ClickHouse/ClickHouse/pull/7360) ([alesapin](https://github.com/alesapin))
-   Make `bloom_filter` type of index supporting `LowCardinality` and `Nullable` [#7363](https://github.com/ClickHouse/ClickHouse/issues/7363) [#7561](https://github.com/ClickHouse/ClickHouse/pull/7561) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Add function `isValidJSON` to check that passed string is a valid json. [#5910](https://github.com/ClickHouse/ClickHouse/issues/5910) [#7293](https://github.com/ClickHouse/ClickHouse/pull/7293) ([Vdimir](https://github.com/Vdimir))
-   Implement `arrayCompact` function [#7328](https://github.com/ClickHouse/ClickHouse/pull/7328) ([Memo](https://github.com/Joeywzr))
-   Created function `hex` for Decimal numbers. It works like `hex(reinterpretAsString())`, but does not delete last zero bytes. [#7355](https://github.com/ClickHouse/ClickHouse/pull/7355) ([Mikhail Korotov](https://github.com/millb))
-   Add `arrayFill` and `arrayReverseFill` functions, which replace elements by other elements in front/back of them in the array. [#7380](https://github.com/ClickHouse/ClickHouse/pull/7380) ([hcz](https://github.com/hczhcz))
-   Add `CRC32IEEE()`/`CRC64()` support [#7480](https://github.com/ClickHouse/ClickHouse/pull/7480) ([Azat Khuzhin](https://github.com/azat))
-   Implement `char` function similar to one in [mysql](https://dev.mysql.com/doc/refman/8.0/en/string-functions.html#function_char) [#7486](https://github.com/ClickHouse/ClickHouse/pull/7486) ([sundyli](https://github.com/sundy-li))
-   Add `bitmapTransform` function. It transforms an array of values in a bitmap to another array of values, the result is a new bitmap [#7598](https://github.com/ClickHouse/ClickHouse/pull/7598) ([Zhichang Yu](https://github.com/yuzhichang))
-   Implemented `javaHashUTF16LE()` function [#7651](https://github.com/ClickHouse/ClickHouse/pull/7651) ([achimbab](https://github.com/achimbab))
-   Add `_shard_num` virtual column for the Distributed engine [#7624](https://github.com/ClickHouse/ClickHouse/pull/7624) ([Azat Khuzhin](https://github.com/azat))

#### Experimental Feature {#experimental-feature}

-   Support for processors (new query execution pipeline) in `MergeTree`. [#7181](https://github.com/ClickHouse/ClickHouse/pull/7181) ([Nikolai Kochetov](https://github.com/KochetovNicolai))

#### Bug Fix {#bug-fix-1}

-   Fix incorrect float parsing in `Values` [#7817](https://github.com/ClickHouse/ClickHouse/issues/7817) [#7870](https://github.com/ClickHouse/ClickHouse/pull/7870) ([tavplubix](https://github.com/tavplubix))
-   Fix rare deadlock which can happen when trace_log is enabled. [#7838](https://github.com/ClickHouse/ClickHouse/pull/7838) ([filimonov](https://github.com/filimonov))
-   Prevent message duplication when producing Kafka table has any MVs selecting from it [#7265](https://github.com/ClickHouse/ClickHouse/pull/7265) ([Ivan](https://github.com/abyss7))
-   Support for `Array(LowCardinality(Nullable(String)))` in `IN`. Resolves [#7364](https://github.com/ClickHouse/ClickHouse/issues/7364) [#7366](https://github.com/ClickHouse/ClickHouse/pull/7366) ([achimbab](https://github.com/achimbab))
-   Add handling of `SQL_TINYINT` and `SQL_BIGINT`, and fix handling of `SQL_FLOAT` data source types in ODBC Bridge. [#7491](https://github.com/ClickHouse/ClickHouse/pull/7491) ([Denis Glazachev](https://github.com/traceon))
-   Fix aggregation (`avg` and quantiles) over empty decimal columns [#7431](https://github.com/ClickHouse/ClickHouse/pull/7431) ([Andrey Konyaev](https://github.com/akonyaev90))
-   Fix `INSERT` into Distributed with `MATERIALIZED` columns [#7377](https://github.com/ClickHouse/ClickHouse/pull/7377) ([Azat Khuzhin](https://github.com/azat))
-   Make `MOVE PARTITION` work if some parts of partition are already on destination disk or volume [#7434](https://github.com/ClickHouse/ClickHouse/pull/7434) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fixed bug with hardlinks failing to be created during mutations in `ReplicatedMergeTree` in multi-disk configurations. [#7558](https://github.com/ClickHouse/ClickHouse/pull/7558) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fixed a bug with a mutation on a MergeTree when whole part remains unchanged and best space is being found on another disk [#7602](https://github.com/ClickHouse/ClickHouse/pull/7602) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fixed bug with `keep_free_space_ratio` not being read from disks configuration [#7645](https://github.com/ClickHouse/ClickHouse/pull/7645) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fix bug with table contains only `Tuple` columns or columns with complex paths. Fixes [7541](https://github.com/ClickHouse/ClickHouse/issues/7541). [#7545](https://github.com/ClickHouse/ClickHouse/pull/7545) ([alesapin](https://github.com/alesapin))
-   Do not account memory for Buffer engine in max_memory_usage limit [#7552](https://github.com/ClickHouse/ClickHouse/pull/7552) ([Azat Khuzhin](https://github.com/azat))
-   Fix final mark usage in `MergeTree` tables ordered by `tuple()`. In rare cases it could lead to `Can't adjust last granule` error while select. [#7639](https://github.com/ClickHouse/ClickHouse/pull/7639) ([Anton Popov](https://github.com/CurtizJ))
-   Fix bug in mutations that have predicate with actions that require context (for example functions for json), which may lead to crashes or strange exceptions. [#7664](https://github.com/ClickHouse/ClickHouse/pull/7664) ([alesapin](https://github.com/alesapin))
-   Fix mismatch of database and table names escaping in `data/` and `shadow/` directories [#7575](https://github.com/ClickHouse/ClickHouse/pull/7575) ([Alexander Burmak](https://github.com/Alex-Burmak))
-   Support duplicated keys in RIGHT\|FULL JOINs, e.g. `ON t.x = u.x AND t.x = u.y`. Fix crash in this case. [#7586](https://github.com/ClickHouse/ClickHouse/pull/7586) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix `Not found column <expression> in block` when joining on expression with RIGHT or FULL JOIN. [#7641](https://github.com/ClickHouse/ClickHouse/pull/7641) ([Artem Zuikov](https://github.com/4ertus2))
-   One more attempt to fix infinite loop in `PrettySpace` format [#7591](https://github.com/ClickHouse/ClickHouse/pull/7591) ([Olga Khvostikova](https://github.com/stavrolia))
-   Fix bug in `concat` function when all arguments were `FixedString` of the same size. [#7635](https://github.com/ClickHouse/ClickHouse/pull/7635) ([alesapin](https://github.com/alesapin))
-   Fixed exception in case of using 1 argument while defining S3, URL and HDFS storages. [#7618](https://github.com/ClickHouse/ClickHouse/pull/7618) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fix scope of the InterpreterSelectQuery for views with query [#7601](https://github.com/ClickHouse/ClickHouse/pull/7601) ([Azat Khuzhin](https://github.com/azat))

#### Improvement {#improvement}

-   `Nullable` columns recognized and NULL-values handled correctly by ODBC-bridge [#7402](https://github.com/ClickHouse/ClickHouse/pull/7402) ([Vasily Nemkov](https://github.com/Enmk))
-   Write current batch for distributed send atomically [#7600](https://github.com/ClickHouse/ClickHouse/pull/7600) ([Azat Khuzhin](https://github.com/azat))
-   Throw an exception if we cannot detect table for column name in query. [#7358](https://github.com/ClickHouse/ClickHouse/pull/7358) ([Artem Zuikov](https://github.com/4ertus2))
-   Add `merge_max_block_size` setting to `MergeTreeSettings` [#7412](https://github.com/ClickHouse/ClickHouse/pull/7412) ([Artem Zuikov](https://github.com/4ertus2))
-   Queries with `HAVING` and without `GROUP BY` assume group by constant. So, `SELECT 1 HAVING 1` now returns a result. [#7496](https://github.com/ClickHouse/ClickHouse/pull/7496) ([Amos Bird](https://github.com/amosbird))
-   Support parsing `(X,)` as tuple similar to python. [#7501](https://github.com/ClickHouse/ClickHouse/pull/7501), [#7562](https://github.com/ClickHouse/ClickHouse/pull/7562) ([Amos Bird](https://github.com/amosbird))
-   Make `range` function behaviors almost like pythonic one. [#7518](https://github.com/ClickHouse/ClickHouse/pull/7518) ([sundyli](https://github.com/sundy-li))
-   Add `constraints` columns to table `system.settings` [#7553](https://github.com/ClickHouse/ClickHouse/pull/7553) ([Vitaly Baranov](https://github.com/vitlibar))
-   Better Null format for tcp handler, so that it’s possible to use `select ignore(<expression>) from table format Null` for perf measure via clickhouse-client [#7606](https://github.com/ClickHouse/ClickHouse/pull/7606) ([Amos Bird](https://github.com/amosbird))
-   Queries like `CREATE TABLE ... AS (SELECT (1, 2))` are parsed correctly [#7542](https://github.com/ClickHouse/ClickHouse/pull/7542) ([hcz](https://github.com/hczhcz))

#### Performance Improvement {#performance-improvement}

-   The performance of aggregation over short string keys is improved. [#6243](https://github.com/ClickHouse/ClickHouse/pull/6243) ([Alexander Kuzmenkov](https://github.com/akuzm), [Amos Bird](https://github.com/amosbird))
-   Run another pass of syntax/expression analysis to get potential optimizations after constant predicates are folded. [#7497](https://github.com/ClickHouse/ClickHouse/pull/7497) ([Amos Bird](https://github.com/amosbird))
-   Use storage meta info to evaluate trivial `SELECT count() FROM table;` [#7510](https://github.com/ClickHouse/ClickHouse/pull/7510) ([Amos Bird](https://github.com/amosbird), [alexey-milovidov](https://github.com/alexey-milovidov))
-   Vectorize processing `arrayReduce` similar to Aggregator `addBatch`. [#7608](https://github.com/ClickHouse/ClickHouse/pull/7608) ([Amos Bird](https://github.com/amosbird))
-   Minor improvements in performance of `Kafka` consumption [#7475](https://github.com/ClickHouse/ClickHouse/pull/7475) ([Ivan](https://github.com/abyss7))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement}

-   Add support for cross-compiling to the CPU architecture AARCH64. Refactor packager script. [#7370](https://github.com/ClickHouse/ClickHouse/pull/7370) [#7539](https://github.com/ClickHouse/ClickHouse/pull/7539) ([Ivan](https://github.com/abyss7))
-   Unpack darwin-x86_64 and linux-aarch64 toolchains into mounted Docker volume when building packages [#7534](https://github.com/ClickHouse/ClickHouse/pull/7534) ([Ivan](https://github.com/abyss7))
-   Update Docker Image for Binary Packager [#7474](https://github.com/ClickHouse/ClickHouse/pull/7474) ([Ivan](https://github.com/abyss7))
-   Fixed compile errors on MacOS Catalina [#7585](https://github.com/ClickHouse/ClickHouse/pull/7585) ([Ernest Poletaev](https://github.com/ernestp))
-   Some refactoring in query analysis logic: split complex class into several simple ones. [#7454](https://github.com/ClickHouse/ClickHouse/pull/7454) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix build without submodules [#7295](https://github.com/ClickHouse/ClickHouse/pull/7295) ([proller](https://github.com/proller))
-   Better `add_globs` in CMake files [#7418](https://github.com/ClickHouse/ClickHouse/pull/7418) ([Amos Bird](https://github.com/amosbird))
-   Remove hardcoded paths in `unwind` target [#7460](https://github.com/ClickHouse/ClickHouse/pull/7460) ([Konstantin Podshumok](https://github.com/podshumok))
-   Allow to use mysql format without ssl [#7524](https://github.com/ClickHouse/ClickHouse/pull/7524) ([proller](https://github.com/proller))

#### Other {#other}

-   Added ANTLR4 grammar for ClickHouse SQL dialect [#7595](https://github.com/ClickHouse/ClickHouse/issues/7595) [#7596](https://github.com/ClickHouse/ClickHouse/pull/7596) ([alexey-milovidov](https://github.com/alexey-milovidov))

## ClickHouse Release 19.16 {#clickhouse-release-v19-16}

#### ClickHouse Release 19.16.14.65, 2020-03-25 {#clickhouse-release-v19-16-14-65-2020-03-25}

-   Fixed up a bug in batched calculations of ternary logical OPs on multiple arguments (more than 10). [#8718](https://github.com/ClickHouse/ClickHouse/pull/8718) ([Alexander Kazakov](https://github.com/Akazz)) This bugfix was backported to version 19.16 by a special request from Altinity.

#### ClickHouse Release 19.16.14.65, 2020-03-05 {#clickhouse-release-v19-16-14-65-2020-03-05}

-   Fix distributed subqueries incompatibility with older CH versions. Fixes [#7851](https://github.com/ClickHouse/ClickHouse/issues/7851)
    [(tabplubix)](https://github.com/tavplubix)
-   When executing `CREATE` query, fold constant expressions in storage engine arguments. Replace empty database name with current database. Fixes [#6508](https://github.com/ClickHouse/ClickHouse/issues/6508), [#3492](https://github.com/ClickHouse/ClickHouse/issues/3492). Also fix check for local address in `ClickHouseDictionarySource`.
    [#9262](https://github.com/ClickHouse/ClickHouse/pull/9262) [(tabplubix)](https://github.com/tavplubix)
-   Now background merges in `*MergeTree` table engines family preserve storage policy volume order more accurately.
    [#8549](https://github.com/ClickHouse/ClickHouse/pull/8549) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Prevent losing data in `Kafka` in rare cases when exception happens after reading suffix but before commit. Fixes [#9378](https://github.com/ClickHouse/ClickHouse/issues/9378). Related: [#7175](https://github.com/ClickHouse/ClickHouse/issues/7175)
    [#9507](https://github.com/ClickHouse/ClickHouse/pull/9507) [(filimonov)](https://github.com/filimonov)
-   Fix bug leading to server termination when trying to use / drop `Kafka` table created with wrong parameters. Fixes [#9494](https://github.com/ClickHouse/ClickHouse/issues/9494). Incorporates [#9507](https://github.com/ClickHouse/ClickHouse/issues/9507).
    [#9513](https://github.com/ClickHouse/ClickHouse/pull/9513) [(filimonov)](https://github.com/filimonov)
-   Allow using `MaterializedView` with subqueries above `Kafka` tables.
    [#8197](https://github.com/ClickHouse/ClickHouse/pull/8197) ([filimonov](https://github.com/filimonov))

#### New Feature {#new-feature-1}

-   Add `deduplicate_blocks_in_dependent_materialized_views` option to control the behaviour of idempotent inserts into tables with materialized views. This new feature was added to the bugfix release by a special request from Altinity.
    [#9070](https://github.com/ClickHouse/ClickHouse/pull/9070) [(urykhy)](https://github.com/urykhy)

### ClickHouse Release 19.16.2.2, 2019-10-30 {#clickhouse-release-v19-16-2-2-2019-10-30}

#### Backward Incompatible Change {#backward-incompatible-change-1}

-   Add missing arity validation for count/counIf.
    [#7095](https://github.com/ClickHouse/ClickHouse/issues/7095)
    [#7298](https://github.com/ClickHouse/ClickHouse/pull/7298) ([Vdimir](https://github.com/Vdimir))
-   Remove legacy `asterisk_left_columns_only` setting (it was disabled by default).
    [#7335](https://github.com/ClickHouse/ClickHouse/pull/7335) ([Artem
    Zuikov](https://github.com/4ertus2))
-   Format strings for Template data format are now specified in files.
    [#7118](https://github.com/ClickHouse/ClickHouse/pull/7118)
    ([tavplubix](https://github.com/tavplubix))

#### New Feature {#new-feature-2}

-   Introduce uniqCombined64() to calculate cardinality greater than UINT_MAX.
    [#7213](https://github.com/ClickHouse/ClickHouse/pull/7213),
    [#7222](https://github.com/ClickHouse/ClickHouse/pull/7222) ([Azat
    Khuzhin](https://github.com/azat))
-   Support Bloom filter indexes on Array columns.
    [#6984](https://github.com/ClickHouse/ClickHouse/pull/6984)
    ([achimbab](https://github.com/achimbab))
-   Add a function `getMacro(name)` that returns String with the value of corresponding `<macros>`
    from server configuration. [#7240](https://github.com/ClickHouse/ClickHouse/pull/7240)
    ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Set two configuration options for a dictionary based on an HTTP source: `credentials` and
    `http-headers`. [#7092](https://github.com/ClickHouse/ClickHouse/pull/7092) ([Guillaume
    Tassery](https://github.com/YiuRULE))
-   Add a new ProfileEvent `Merge` that counts the number of launched background merges.
    [#7093](https://github.com/ClickHouse/ClickHouse/pull/7093) ([Mikhail
    Korotov](https://github.com/millb))
-   Add fullHostName function that returns a fully qualified domain name.
    [#7263](https://github.com/ClickHouse/ClickHouse/issues/7263)
    [#7291](https://github.com/ClickHouse/ClickHouse/pull/7291) ([sundyli](https://github.com/sundy-li))
-   Add function `arraySplit` and `arrayReverseSplit` which split an array by “cut off”
    conditions. They are useful in time sequence handling.
    [#7294](https://github.com/ClickHouse/ClickHouse/pull/7294) ([hcz](https://github.com/hczhcz))
-   Add new functions that return the Array of all matched indices in multiMatch family of functions.
    [#7299](https://github.com/ClickHouse/ClickHouse/pull/7299) ([Danila
    Kutenin](https://github.com/danlark1))
-   Add a new database engine `Lazy` that is optimized for storing a large number of small -Log
    tables. [#7171](https://github.com/ClickHouse/ClickHouse/pull/7171) ([Nikita
    Vasilev](https://github.com/nikvas0))
-   Add aggregate functions groupBitmapAnd, -Or, -Xor for bitmap columns. [#7109](https://github.com/ClickHouse/ClickHouse/pull/7109) ([Zhichang
    Yu](https://github.com/yuzhichang))
-   Add aggregate function combinators -OrNull and -OrDefault, which return null
    or default values when there is nothing to aggregate.
    [#7331](https://github.com/ClickHouse/ClickHouse/pull/7331)
    ([hcz](https://github.com/hczhcz))
-   Introduce CustomSeparated data format that supports custom escaping and
    delimiter rules. [#7118](https://github.com/ClickHouse/ClickHouse/pull/7118)
    ([tavplubix](https://github.com/tavplubix))
-   Support Redis as source of external dictionary. [#4361](https://github.com/ClickHouse/ClickHouse/pull/4361) [#6962](https://github.com/ClickHouse/ClickHouse/pull/6962) ([comunodi](https://github.com/comunodi), [Anton
    Popov](https://github.com/CurtizJ))

#### Bug Fix {#bug-fix-2}

-   Fix wrong query result if it has `WHERE IN (SELECT ...)` section and `optimize_read_in_order` is
    used. [#7371](https://github.com/ClickHouse/ClickHouse/pull/7371) ([Anton
    Popov](https://github.com/CurtizJ))
-   Disabled MariaDB authentication plugin, which depends on files outside of project.
    [#7140](https://github.com/ClickHouse/ClickHouse/pull/7140) ([Yuriy
    Baranov](https://github.com/yurriy))
-   Fix exception `Cannot convert column ... because it is constant but values of constants are different in source and result` which could rarely happen when functions `now()`, `today()`,
    `yesterday()`, `randConstant()` are used.
    [#7156](https://github.com/ClickHouse/ClickHouse/pull/7156) ([Nikolai
    Kochetov](https://github.com/KochetovNicolai))
-   Fixed issue of using HTTP keep alive timeout instead of TCP keep alive timeout.
    [#7351](https://github.com/ClickHouse/ClickHouse/pull/7351) ([Vasily
    Nemkov](https://github.com/Enmk))
-   Fixed a segmentation fault in groupBitmapOr (issue [#7109](https://github.com/ClickHouse/ClickHouse/issues/7109)).
    [#7289](https://github.com/ClickHouse/ClickHouse/pull/7289) ([Zhichang
    Yu](https://github.com/yuzhichang))
-   For materialized views the commit for Kafka is called after all data were written.
    [#7175](https://github.com/ClickHouse/ClickHouse/pull/7175) ([Ivan](https://github.com/abyss7))
-   Fixed wrong `duration_ms` value in `system.part_log` table. It was ten times off.
    [#7172](https://github.com/ClickHouse/ClickHouse/pull/7172) ([Vladimir
    Chebotarev](https://github.com/excitoon))
-   A quick fix to resolve crash in LIVE VIEW table and re-enabling all LIVE VIEW tests.
    [#7201](https://github.com/ClickHouse/ClickHouse/pull/7201)
    ([vzakaznikov](https://github.com/vzakaznikov))
-   Serialize NULL values correctly in min/max indexes of MergeTree parts.
    [#7234](https://github.com/ClickHouse/ClickHouse/pull/7234) ([Alexander
    Kuzmenkov](https://github.com/akuzm))
-   Don’t put virtual columns to .sql metadata when table is created as `CREATE TABLE AS`.
    [#7183](https://github.com/ClickHouse/ClickHouse/pull/7183) ([Ivan](https://github.com/abyss7))
-   Fix segmentation fault in `ATTACH PART` query.
    [#7185](https://github.com/ClickHouse/ClickHouse/pull/7185)
    ([alesapin](https://github.com/alesapin))
-   Fix wrong result for some queries given by the optimization of empty IN subqueries and empty
    INNER/RIGHT JOIN. [#7284](https://github.com/ClickHouse/ClickHouse/pull/7284) ([Nikolai
    Kochetov](https://github.com/KochetovNicolai))
-   Fixing AddressSanitizer error in the LIVE VIEW getHeader() method.
    [#7271](https://github.com/ClickHouse/ClickHouse/pull/7271)
    ([vzakaznikov](https://github.com/vzakaznikov))

#### Improvement {#improvement-1}

-   Add a message in case of queue_wait_max_ms wait takes place.
    [#7390](https://github.com/ClickHouse/ClickHouse/pull/7390) ([Azat
    Khuzhin](https://github.com/azat))
-   Made setting `s3_min_upload_part_size` table-level.
    [#7059](https://github.com/ClickHouse/ClickHouse/pull/7059) ([Vladimir
    Chebotarev](https://github.com/excitoon))
-   Check TTL in StorageFactory. [#7304](https://github.com/ClickHouse/ClickHouse/pull/7304)
    ([sundyli](https://github.com/sundy-li))
-   Squash left-hand blocks in partial merge join (optimization).
    [#7122](https://github.com/ClickHouse/ClickHouse/pull/7122) ([Artem
    Zuikov](https://github.com/4ertus2))
-   Do not allow non-deterministic functions in mutations of Replicated table engines, because this
    can introduce inconsistencies between replicas.
    [#7247](https://github.com/ClickHouse/ClickHouse/pull/7247) ([Alexander
    Kazakov](https://github.com/Akazz))
-   Disable memory tracker while converting exception stack trace to string. It can prevent the loss
    of error messages of type `Memory limit exceeded` on server, which caused the `Attempt to read after eof` exception on client. [#7264](https://github.com/ClickHouse/ClickHouse/pull/7264)
    ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Miscellaneous format improvements. Resolves
    [#6033](https://github.com/ClickHouse/ClickHouse/issues/6033),
    [#2633](https://github.com/ClickHouse/ClickHouse/issues/2633),
    [#6611](https://github.com/ClickHouse/ClickHouse/issues/6611),
    [#6742](https://github.com/ClickHouse/ClickHouse/issues/6742)
    [#7215](https://github.com/ClickHouse/ClickHouse/pull/7215)
    ([tavplubix](https://github.com/tavplubix))
-   ClickHouse ignores values on the right side of IN operator that are not convertible to the left
    side type. Make it work properly for compound types – Array and Tuple.
    [#7283](https://github.com/ClickHouse/ClickHouse/pull/7283) ([Alexander
    Kuzmenkov](https://github.com/akuzm))
-   Support missing inequalities for ASOF JOIN. It’s possible to join less-or-equal variant and strict
    greater and less variants for ASOF column in ON syntax.
    [#7282](https://github.com/ClickHouse/ClickHouse/pull/7282) ([Artem
    Zuikov](https://github.com/4ertus2))
-   Optimize partial merge join. [#7070](https://github.com/ClickHouse/ClickHouse/pull/7070)
    ([Artem Zuikov](https://github.com/4ertus2))
-   Do not use more than 98K of memory in uniqCombined functions.
    [#7236](https://github.com/ClickHouse/ClickHouse/pull/7236),
    [#7270](https://github.com/ClickHouse/ClickHouse/pull/7270) ([Azat
    Khuzhin](https://github.com/azat))
-   Flush parts of right-hand joining table on disk in PartialMergeJoin (if there is not enough
    memory). Load data back when needed. [#7186](https://github.com/ClickHouse/ClickHouse/pull/7186)
    ([Artem Zuikov](https://github.com/4ertus2))

#### Performance Improvement {#performance-improvement-1}

-   Speed up joinGet with const arguments by avoiding data duplication.
    [#7359](https://github.com/ClickHouse/ClickHouse/pull/7359) ([Amos
    Bird](https://github.com/amosbird))
-   Return early if the subquery is empty.
    [#7007](https://github.com/ClickHouse/ClickHouse/pull/7007) ([小路](https://github.com/nicelulu))
-   Optimize parsing of SQL expression in Values.
    [#6781](https://github.com/ClickHouse/ClickHouse/pull/6781)
    ([tavplubix](https://github.com/tavplubix))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-1}

-   Disable some contribs for cross-compilation to Mac OS.
    [#7101](https://github.com/ClickHouse/ClickHouse/pull/7101) ([Ivan](https://github.com/abyss7))
-   Add missing linking with PocoXML for clickhouse_common_io.
    [#7200](https://github.com/ClickHouse/ClickHouse/pull/7200) ([Azat
    Khuzhin](https://github.com/azat))
-   Accept multiple test filter arguments in clickhouse-test.
    [#7226](https://github.com/ClickHouse/ClickHouse/pull/7226) ([Alexander
    Kuzmenkov](https://github.com/akuzm))
-   Enable musl and jemalloc for ARM. [#7300](https://github.com/ClickHouse/ClickHouse/pull/7300)
    ([Amos Bird](https://github.com/amosbird))
-   Added `--client-option` parameter to `clickhouse-test` to pass additional parameters to client.
    [#7277](https://github.com/ClickHouse/ClickHouse/pull/7277) ([Nikolai
    Kochetov](https://github.com/KochetovNicolai))
-   Preserve existing configs on rpm package upgrade.
    [#7103](https://github.com/ClickHouse/ClickHouse/pull/7103)
    ([filimonov](https://github.com/filimonov))
-   Fix errors detected by PVS. [#7153](https://github.com/ClickHouse/ClickHouse/pull/7153) ([Artem
    Zuikov](https://github.com/4ertus2))
-   Fix build for Darwin. [#7149](https://github.com/ClickHouse/ClickHouse/pull/7149)
    ([Ivan](https://github.com/abyss7))
-   glibc 2.29 compatibility. [#7142](https://github.com/ClickHouse/ClickHouse/pull/7142) ([Amos
    Bird](https://github.com/amosbird))
-   Make sure dh_clean does not touch potential source files.
    [#7205](https://github.com/ClickHouse/ClickHouse/pull/7205) ([Amos
    Bird](https://github.com/amosbird))
-   Attempt to avoid conflict when updating from altinity rpm - it has config file packaged separately
    in clickhouse-server-common. [#7073](https://github.com/ClickHouse/ClickHouse/pull/7073)
    ([filimonov](https://github.com/filimonov))
-   Optimize some header files for faster rebuilds.
    [#7212](https://github.com/ClickHouse/ClickHouse/pull/7212),
    [#7231](https://github.com/ClickHouse/ClickHouse/pull/7231) ([Alexander
    Kuzmenkov](https://github.com/akuzm))
-   Add performance tests for Date and DateTime. [#7332](https://github.com/ClickHouse/ClickHouse/pull/7332) ([Vasily
    Nemkov](https://github.com/Enmk))
-   Fix some tests that contained non-deterministic mutations.
    [#7132](https://github.com/ClickHouse/ClickHouse/pull/7132) ([Alexander
    Kazakov](https://github.com/Akazz))
-   Add build with MemorySanitizer to CI. [#7066](https://github.com/ClickHouse/ClickHouse/pull/7066)
    ([Alexander Kuzmenkov](https://github.com/akuzm))
-   Avoid use of uninitialized values in MetricsTransmitter.
    [#7158](https://github.com/ClickHouse/ClickHouse/pull/7158) ([Azat
    Khuzhin](https://github.com/azat))
-   Fix some issues in Fields found by MemorySanitizer.
    [#7135](https://github.com/ClickHouse/ClickHouse/pull/7135),
    [#7179](https://github.com/ClickHouse/ClickHouse/pull/7179) ([Alexander
    Kuzmenkov](https://github.com/akuzm)), [#7376](https://github.com/ClickHouse/ClickHouse/pull/7376)
    ([Amos Bird](https://github.com/amosbird))
-   Fix undefined behavior in murmurhash32. [#7388](https://github.com/ClickHouse/ClickHouse/pull/7388) ([Amos
    Bird](https://github.com/amosbird))
-   Fix undefined behavior in StoragesInfoStream. [#7384](https://github.com/ClickHouse/ClickHouse/pull/7384)
    ([tavplubix](https://github.com/tavplubix))
-   Fixed constant expressions folding for external database engines (MySQL, ODBC, JDBC). In previous
    versions it wasn’t working for multiple constant expressions and was not working at all for Date,
    DateTime and UUID. This fixes [#7245](https://github.com/ClickHouse/ClickHouse/issues/7245)
    [#7252](https://github.com/ClickHouse/ClickHouse/pull/7252)
    ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixing ThreadSanitizer data race error in the LIVE VIEW when accessing no_users_thread variable.
    [#7353](https://github.com/ClickHouse/ClickHouse/pull/7353)
    ([vzakaznikov](https://github.com/vzakaznikov))
-   Get rid of malloc symbols in libcommon
    [#7134](https://github.com/ClickHouse/ClickHouse/pull/7134),
    [#7065](https://github.com/ClickHouse/ClickHouse/pull/7065) ([Amos
    Bird](https://github.com/amosbird))
-   Add global flag ENABLE_LIBRARIES for disabling all libraries.
    [#7063](https://github.com/ClickHouse/ClickHouse/pull/7063)
    ([proller](https://github.com/proller))

#### Code Cleanup {#code-cleanup}

-   Generalize configuration repository to prepare for DDL for Dictionaries. [#7155](https://github.com/ClickHouse/ClickHouse/pull/7155)
    ([alesapin](https://github.com/alesapin))
-   Parser for dictionaries DDL without any semantic.
    [#7209](https://github.com/ClickHouse/ClickHouse/pull/7209)
    ([alesapin](https://github.com/alesapin))
-   Split ParserCreateQuery into different smaller parsers.
    [#7253](https://github.com/ClickHouse/ClickHouse/pull/7253)
    ([alesapin](https://github.com/alesapin))
-   Small refactoring and renaming near external dictionaries.
    [#7111](https://github.com/ClickHouse/ClickHouse/pull/7111)
    ([alesapin](https://github.com/alesapin))
-   Refactor some code to prepare for role-based access control. [#7235](https://github.com/ClickHouse/ClickHouse/pull/7235) ([Vitaly
    Baranov](https://github.com/vitlibar))
-   Some improvements in DatabaseOrdinary code.
    [#7086](https://github.com/ClickHouse/ClickHouse/pull/7086) ([Nikita
    Vasilev](https://github.com/nikvas0))
-   Do not use iterators in find() and emplace() methods of hash tables.
    [#7026](https://github.com/ClickHouse/ClickHouse/pull/7026) ([Alexander
    Kuzmenkov](https://github.com/akuzm))
-   Fix getMultipleValuesFromConfig in case when parameter root is not empty. [#7374](https://github.com/ClickHouse/ClickHouse/pull/7374)
    ([Mikhail Korotov](https://github.com/millb))
-   Remove some copy-paste (TemporaryFile and TemporaryFileStream)
    [#7166](https://github.com/ClickHouse/ClickHouse/pull/7166) ([Artem
    Zuikov](https://github.com/4ertus2))
-   Improved code readability a little bit (`MergeTreeData::getActiveContainingPart`).
    [#7361](https://github.com/ClickHouse/ClickHouse/pull/7361) ([Vladimir
    Chebotarev](https://github.com/excitoon))
-   Wait for all scheduled jobs, which are using local objects, if `ThreadPool::schedule(...)` throws
    an exception. Rename `ThreadPool::schedule(...)` to `ThreadPool::scheduleOrThrowOnError(...)` and
    fix comments to make obvious that it may throw.
    [#7350](https://github.com/ClickHouse/ClickHouse/pull/7350)
    ([tavplubix](https://github.com/tavplubix))

## ClickHouse Release 19.15 {#clickhouse-release-19-15}

### ClickHouse Release 19.15.4.10, 2019-10-31 {#clickhouse-release-19-15-4-10-2019-10-31}

#### Bug Fix {#bug-fix-3}

-   Added handling of SQL_TINYINT and SQL_BIGINT, and fix handling of SQL_FLOAT data source types in ODBC Bridge.
    [#7491](https://github.com/ClickHouse/ClickHouse/pull/7491) ([Denis Glazachev](https://github.com/traceon))
-   Allowed to have some parts on destination disk or volume in MOVE PARTITION.
    [#7434](https://github.com/ClickHouse/ClickHouse/pull/7434) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fixed NULL-values in nullable columns through ODBC-bridge.
    [#7402](https://github.com/ClickHouse/ClickHouse/pull/7402) ([Vasily Nemkov](https://github.com/Enmk))
-   Fixed INSERT into Distributed non local node with MATERIALIZED columns.
    [#7377](https://github.com/ClickHouse/ClickHouse/pull/7377) ([Azat Khuzhin](https://github.com/azat))
-   Fixed function getMultipleValuesFromConfig.
    [#7374](https://github.com/ClickHouse/ClickHouse/pull/7374) ([Mikhail Korotov](https://github.com/millb))
-   Fixed issue of using HTTP keep alive timeout instead of TCP keep alive timeout.
    [#7351](https://github.com/ClickHouse/ClickHouse/pull/7351) ([Vasily Nemkov](https://github.com/Enmk))
-   Wait for all jobs to finish on exception (fixes rare segfaults).
    [#7350](https://github.com/ClickHouse/ClickHouse/pull/7350) ([tavplubix](https://github.com/tavplubix))
-   Don’t push to MVs when inserting into Kafka table.
    [#7265](https://github.com/ClickHouse/ClickHouse/pull/7265) ([Ivan](https://github.com/abyss7))
-   Disable memory tracker for exception stack.
    [#7264](https://github.com/ClickHouse/ClickHouse/pull/7264) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed bad code in transforming query for external database.
    [#7252](https://github.com/ClickHouse/ClickHouse/pull/7252) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Avoid use of uninitialized values in MetricsTransmitter.
    [#7158](https://github.com/ClickHouse/ClickHouse/pull/7158) ([Azat Khuzhin](https://github.com/azat))
-   Added example config with macros for tests ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.15.3.6, 2019-10-09 {#clickhouse-release-19-15-3-6-2019-10-09}

#### Bug Fix {#bug-fix-4}

-   Fixed bad_variant in hashed dictionary.
    ([alesapin](https://github.com/alesapin))
-   Fixed up bug with segmentation fault in ATTACH PART query.
    ([alesapin](https://github.com/alesapin))
-   Fixed time calculation in `MergeTreeData`.
    ([Vladimir Chebotarev](https://github.com/excitoon))
-   Commit to Kafka explicitly after the writing is finalized.
    [#7175](https://github.com/ClickHouse/ClickHouse/pull/7175) ([Ivan](https://github.com/abyss7))
-   Serialize NULL values correctly in min/max indexes of MergeTree parts.
    [#7234](https://github.com/ClickHouse/ClickHouse/pull/7234) ([Alexander Kuzmenkov](https://github.com/akuzm))

### ClickHouse Release 19.15.2.2, 2019-10-01 {#clickhouse-release-19-15-2-2-2019-10-01}

#### New Feature {#new-feature-3}

-   Tiered storage: support to use multiple storage volumes for tables with MergeTree engine. It’s possible to store fresh data on SSD and automatically move old data to HDD. ([example](https://clickhouse.github.io/clickhouse-presentations/meetup30/new_features/#12)). [#4918](https://github.com/ClickHouse/ClickHouse/pull/4918) ([Igr](https://github.com/ObjatieGroba)) [#6489](https://github.com/ClickHouse/ClickHouse/pull/6489) ([alesapin](https://github.com/alesapin))
-   Add table function `input` for reading incoming data in `INSERT SELECT` query. [#5450](https://github.com/ClickHouse/ClickHouse/pull/5450) ([palasonic1](https://github.com/palasonic1)) [#6832](https://github.com/ClickHouse/ClickHouse/pull/6832) ([Anton Popov](https://github.com/CurtizJ))
-   Add a `sparse_hashed` dictionary layout, that is functionally equivalent to the `hashed` layout, but is more memory efficient. It uses about twice as less memory at the cost of slower value retrieval. [#6894](https://github.com/ClickHouse/ClickHouse/pull/6894) ([Azat Khuzhin](https://github.com/azat))
-   Implement ability to define list of users for access to dictionaries. Only current connected database using. [#6907](https://github.com/ClickHouse/ClickHouse/pull/6907) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Add `LIMIT` option to `SHOW` query. [#6944](https://github.com/ClickHouse/ClickHouse/pull/6944) ([Philipp Malkovsky](https://github.com/malkfilipp))
-   Add `bitmapSubsetLimit(bitmap, range_start, limit)` function, that returns subset of the smallest `limit` values in set that is no smaller than `range_start`. [#6957](https://github.com/ClickHouse/ClickHouse/pull/6957) ([Zhichang Yu](https://github.com/yuzhichang))
-   Add `bitmapMin` and `bitmapMax` functions. [#6970](https://github.com/ClickHouse/ClickHouse/pull/6970) ([Zhichang Yu](https://github.com/yuzhichang))
-   Add function `repeat` related to [issue-6648](https://github.com/ClickHouse/ClickHouse/issues/6648) [#6999](https://github.com/ClickHouse/ClickHouse/pull/6999) ([flynn](https://github.com/ucasFL))

#### Experimental Feature {#experimental-feature-1}

-   Implement (in memory) Merge Join variant that does not change current pipeline. Result is partially sorted by merge key. Set `partial_merge_join = 1` to use this feature. The Merge Join is still in development. [#6940](https://github.com/ClickHouse/ClickHouse/pull/6940) ([Artem Zuikov](https://github.com/4ertus2))
-   Add `S3` engine and table function. It is still in development (no authentication support yet). [#5596](https://github.com/ClickHouse/ClickHouse/pull/5596) ([Vladimir Chebotarev](https://github.com/excitoon))

#### Improvement {#improvement-2}

-   Every message read from Kafka is inserted atomically. This resolves almost all known issues with Kafka engine. [#6950](https://github.com/ClickHouse/ClickHouse/pull/6950) ([Ivan](https://github.com/abyss7))
-   Improvements for failover of Distributed queries. Shorten recovery time, also it is now configurable and can be seen in `system.clusters`. [#6399](https://github.com/ClickHouse/ClickHouse/pull/6399) ([Vasily Nemkov](https://github.com/Enmk))
-   Support numeric values for Enums directly in `IN` section. #6766 [#6941](https://github.com/ClickHouse/ClickHouse/pull/6941) ([dimarub2000](https://github.com/dimarub2000))
-   Support (optional, disabled by default) redirects on URL storage. [#6914](https://github.com/ClickHouse/ClickHouse/pull/6914) ([maqroll](https://github.com/maqroll))
-   Add information message when client with an older version connects to a server. [#6893](https://github.com/ClickHouse/ClickHouse/pull/6893) ([Philipp Malkovsky](https://github.com/malkfilipp))
-   Remove maximum backoff sleep time limit for sending data in Distributed tables [#6895](https://github.com/ClickHouse/ClickHouse/pull/6895) ([Azat Khuzhin](https://github.com/azat))
-   Add ability to send profile events (counters) with cumulative values to graphite. It can be enabled under `<events_cumulative>` in server `config.xml`. [#6969](https://github.com/ClickHouse/ClickHouse/pull/6969) ([Azat Khuzhin](https://github.com/azat))
-   Add automatically cast type `T` to `LowCardinality(T)` while inserting data in column of type `LowCardinality(T)` in Native format via HTTP. [#6891](https://github.com/ClickHouse/ClickHouse/pull/6891) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Add ability to use function `hex` without using `reinterpretAsString` for `Float32`, `Float64`. [#7024](https://github.com/ClickHouse/ClickHouse/pull/7024) ([Mikhail Korotov](https://github.com/millb))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-2}

-   Add gdb-index to clickhouse binary with debug info. It will speed up startup time of `gdb`. [#6947](https://github.com/ClickHouse/ClickHouse/pull/6947) ([alesapin](https://github.com/alesapin))
-   Speed up deb packaging with patched dpkg-deb which uses `pigz`. [#6960](https://github.com/ClickHouse/ClickHouse/pull/6960) ([alesapin](https://github.com/alesapin))
-   Set `enable_fuzzing = 1` to enable libfuzzer instrumentation of all the project code. [#7042](https://github.com/ClickHouse/ClickHouse/pull/7042) ([kyprizel](https://github.com/kyprizel))
-   Add split build smoke test in CI. [#7061](https://github.com/ClickHouse/ClickHouse/pull/7061) ([alesapin](https://github.com/alesapin))
-   Add build with MemorySanitizer to CI. [#7066](https://github.com/ClickHouse/ClickHouse/pull/7066) ([Alexander Kuzmenkov](https://github.com/akuzm))
-   Replace `libsparsehash` with `sparsehash-c11` [#6965](https://github.com/ClickHouse/ClickHouse/pull/6965) ([Azat Khuzhin](https://github.com/azat))

#### Bug Fix {#bug-fix-5}

-   Fixed performance degradation of index analysis on complex keys on large tables. This fixes #6924. [#7075](https://github.com/ClickHouse/ClickHouse/pull/7075) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix logical error causing segfaults when selecting from Kafka empty topic. [#6909](https://github.com/ClickHouse/ClickHouse/pull/6909) ([Ivan](https://github.com/abyss7))
-   Fix too early MySQL connection close in `MySQLBlockInputStream.cpp`. [#6882](https://github.com/ClickHouse/ClickHouse/pull/6882) ([Clément Rodriguez](https://github.com/clemrodriguez))
-   Returned support for very old Linux kernels (fix [#6841](https://github.com/ClickHouse/ClickHouse/issues/6841)) [#6853](https://github.com/ClickHouse/ClickHouse/pull/6853) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix possible data loss in `insert select` query in case of empty block in input stream. #6834 #6862 [#6911](https://github.com/ClickHouse/ClickHouse/pull/6911) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix for function `АrrayEnumerateUniqRanked` with empty arrays in params [#6928](https://github.com/ClickHouse/ClickHouse/pull/6928) ([proller](https://github.com/proller))
-   Fix complex queries with array joins and global subqueries. [#6934](https://github.com/ClickHouse/ClickHouse/pull/6934) ([Ivan](https://github.com/abyss7))
-   Fix `Unknown identifier` error in ORDER BY and GROUP BY with multiple JOINs [#7022](https://github.com/ClickHouse/ClickHouse/pull/7022) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed `MSan` warning while executing function with `LowCardinality` argument. [#7062](https://github.com/ClickHouse/ClickHouse/pull/7062) ([Nikolai Kochetov](https://github.com/KochetovNicolai))

#### Backward Incompatible Change {#backward-incompatible-change-2}

-   Changed serialization format of bitmap\* aggregate function states to improve performance. Serialized states of bitmap\* from previous versions cannot be read. [#6908](https://github.com/ClickHouse/ClickHouse/pull/6908) ([Zhichang Yu](https://github.com/yuzhichang))

## ClickHouse Release 19.14 {#clickhouse-release-19-14}

### ClickHouse Release 19.14.7.15, 2019-10-02 {#clickhouse-release-19-14-7-15-2019-10-02}

#### Bug Fix {#bug-fix-6}

-   This release also contains all bug fixes from 19.11.12.69.
-   Fixed compatibility for distributed queries between 19.14 and earlier versions. This fixes [#7068](https://github.com/ClickHouse/ClickHouse/issues/7068). [#7069](https://github.com/ClickHouse/ClickHouse/pull/7069) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.14.6.12, 2019-09-19 {#clickhouse-release-19-14-6-12-2019-09-19}

#### Bug Fix {#bug-fix-7}

-   Fix for function `АrrayEnumerateUniqRanked` with empty arrays in params. [#6928](https://github.com/ClickHouse/ClickHouse/pull/6928) ([proller](https://github.com/proller))
-   Fixed subquery name in queries with `ARRAY JOIN` and `GLOBAL IN subquery` with alias. Use subquery alias for external table name if it is specified. [#6934](https://github.com/ClickHouse/ClickHouse/pull/6934) ([Ivan](https://github.com/abyss7))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-3}

-   Fix [flapping](https://clickhouse-test-reports.s3.yandex.net/6944/aab95fd5175a513413c7395a73a82044bdafb906/functional_stateless_tests_(debug).html) test `00715_fetch_merged_or_mutated_part_zookeeper` by rewriting it to a shell scripts because it needs to wait for mutations to apply. [#6977](https://github.com/ClickHouse/ClickHouse/pull/6977) ([Alexander Kazakov](https://github.com/Akazz))
-   Fixed UBSan and MemSan failure in function `groupUniqArray` with emtpy array argument. It was caused by placing of empty `PaddedPODArray` into hash table zero cell because constructor for zero cell value was not called. [#6937](https://github.com/ClickHouse/ClickHouse/pull/6937) ([Amos Bird](https://github.com/amosbird))

### ClickHouse Release 19.14.3.3, 2019-09-10 {#clickhouse-release-19-14-3-3-2019-09-10}

#### New Feature {#new-feature-4}

-   `WITH FILL` modifier for `ORDER BY`. (continuation of [#5069](https://github.com/ClickHouse/ClickHouse/issues/5069)) [#6610](https://github.com/ClickHouse/ClickHouse/pull/6610) ([Anton Popov](https://github.com/CurtizJ))
-   `WITH TIES` modifier for `LIMIT`. (continuation of [#5069](https://github.com/ClickHouse/ClickHouse/issues/5069)) [#6610](https://github.com/ClickHouse/ClickHouse/pull/6610) ([Anton Popov](https://github.com/CurtizJ))
-   Parse unquoted `NULL` literal as NULL (if setting `format_csv_unquoted_null_literal_as_null=1`). Initialize null fields with default values if data type of this field is not nullable (if setting `input_format_null_as_default=1`). [#5990](https://github.com/ClickHouse/ClickHouse/issues/5990) [#6055](https://github.com/ClickHouse/ClickHouse/pull/6055) ([tavplubix](https://github.com/tavplubix))
-   Support for wildcards in paths of table functions `file` and `hdfs`. If the path contains wildcards, the table will be readonly. Example of usage: `select * from hdfs('hdfs://hdfs1:9000/some_dir/another_dir/*/file{0..9}{0..9}')` and `select * from file('some_dir/{some_file,another_file,yet_another}.tsv', 'TSV', 'value UInt32')`. [#6092](https://github.com/ClickHouse/ClickHouse/pull/6092) ([Olga Khvostikova](https://github.com/stavrolia))
-   New `system.metric_log` table which stores values of `system.events` and `system.metrics` with specified time interval. [#6363](https://github.com/ClickHouse/ClickHouse/issues/6363) [#6467](https://github.com/ClickHouse/ClickHouse/pull/6467) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)) [#6530](https://github.com/ClickHouse/ClickHouse/pull/6530) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Allow to write ClickHouse text logs to `system.text_log` table. [#6037](https://github.com/ClickHouse/ClickHouse/issues/6037) [#6103](https://github.com/ClickHouse/ClickHouse/pull/6103) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)) [#6164](https://github.com/ClickHouse/ClickHouse/pull/6164) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Show private symbols in stack traces (this is done via parsing symbol tables of ELF files). Added information about file and line number in stack traces if debug info is present. Speedup symbol name lookup with indexing symbols present in program. Added new SQL functions for introspection: `demangle` and `addressToLine`. Renamed function `symbolizeAddress` to `addressToSymbol` for consistency. Function `addressToSymbol` will return mangled name for performance reasons and you have to apply `demangle`. Added setting `allow_introspection_functions` which is turned off by default. [#6201](https://github.com/ClickHouse/ClickHouse/pull/6201) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Table function `values` (the name is case-insensitive). It allows to read from `VALUES` list proposed in [#5984](https://github.com/ClickHouse/ClickHouse/issues/5984). Example: `SELECT * FROM VALUES('a UInt64, s String', (1, 'one'), (2, 'two'), (3, 'three'))`. [#6217](https://github.com/ClickHouse/ClickHouse/issues/6217). [#6209](https://github.com/ClickHouse/ClickHouse/pull/6209) ([dimarub2000](https://github.com/dimarub2000))
-   Added an ability to alter storage settings. Syntax: `ALTER TABLE <table> MODIFY SETTING <setting> = <value>`. [#6366](https://github.com/ClickHouse/ClickHouse/pull/6366) [#6669](https://github.com/ClickHouse/ClickHouse/pull/6669) [#6685](https://github.com/ClickHouse/ClickHouse/pull/6685) ([alesapin](https://github.com/alesapin))
-   Support for removing of detached parts. Syntax: `ALTER TABLE <table_name> DROP DETACHED PART '<part_id>'`. [#6158](https://github.com/ClickHouse/ClickHouse/pull/6158) ([tavplubix](https://github.com/tavplubix))
-   Table constraints. Allows to add constraint to table definition which will be checked at insert. [#5273](https://github.com/ClickHouse/ClickHouse/pull/5273) ([Gleb Novikov](https://github.com/NanoBjorn)) [#6652](https://github.com/ClickHouse/ClickHouse/pull/6652) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Suppport for cascaded materialized views. [#6324](https://github.com/ClickHouse/ClickHouse/pull/6324) ([Amos Bird](https://github.com/amosbird))
-   Turn on query profiler by default to sample every query execution thread once a second. [#6283](https://github.com/ClickHouse/ClickHouse/pull/6283) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Input format `ORC`. [#6454](https://github.com/ClickHouse/ClickHouse/pull/6454) [#6703](https://github.com/ClickHouse/ClickHouse/pull/6703) ([akonyaev90](https://github.com/akonyaev90))
-   Added two new functions: `sigmoid` and `tanh` (that are useful for machine learning applications). [#6254](https://github.com/ClickHouse/ClickHouse/pull/6254) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Function `hasToken(haystack, token)`, `hasTokenCaseInsensitive(haystack, token)` to check if given token is in haystack. Token is a maximal length substring between two non alphanumeric ASCII characters (or boundaries of haystack). Token must be a constant string. Supported by tokenbf_v1 index specialization. [#6596](https://github.com/ClickHouse/ClickHouse/pull/6596), [#6662](https://github.com/ClickHouse/ClickHouse/pull/6662) ([Vasily Nemkov](https://github.com/Enmk))
-   New function `neighbor(value, offset[, default_value])`. Allows to reach prev/next value within column in a block of data. [#5925](https://github.com/ClickHouse/ClickHouse/pull/5925) ([Alex Krash](https://github.com/alex-krash)) [6685365ab8c5b74f9650492c88a012596eb1b0c6](https://github.com/ClickHouse/ClickHouse/commit/6685365ab8c5b74f9650492c88a012596eb1b0c6) [341e2e4587a18065c2da1ca888c73389f48ce36c](https://github.com/ClickHouse/ClickHouse/commit/341e2e4587a18065c2da1ca888c73389f48ce36c) [Alexey Milovidov](https://github.com/alexey-milovidov)
-   Created a function `currentUser()`, returning login of authorized user. Added alias `user()` for compatibility with MySQL. [#6470](https://github.com/ClickHouse/ClickHouse/pull/6470) ([Alex Krash](https://github.com/alex-krash))
-   New aggregate functions `quantilesExactInclusive` and `quantilesExactExclusive` which were proposed in [#5885](https://github.com/ClickHouse/ClickHouse/issues/5885). [#6477](https://github.com/ClickHouse/ClickHouse/pull/6477) ([dimarub2000](https://github.com/dimarub2000))
-   Function `bitmapRange(bitmap, range_begin, range_end)` which returns new set with specified range (not include the `range_end`). [#6314](https://github.com/ClickHouse/ClickHouse/pull/6314) ([Zhichang Yu](https://github.com/yuzhichang))
-   Function `geohashesInBox(longitude_min, latitude_min, longitude_max, latitude_max, precision)` which creates array of precision-long strings of geohash-boxes covering provided area. [#6127](https://github.com/ClickHouse/ClickHouse/pull/6127) ([Vasily Nemkov](https://github.com/Enmk))
-   Implement support for INSERT query with `Kafka` tables. [#6012](https://github.com/ClickHouse/ClickHouse/pull/6012) ([Ivan](https://github.com/abyss7))
-   Added support for `_partition` and `_timestamp` virtual columns to Kafka engine. [#6400](https://github.com/ClickHouse/ClickHouse/pull/6400) ([Ivan](https://github.com/abyss7))
-   Possibility to remove sensitive data from `query_log`, server logs, process list with regexp-based rules. [#5710](https://github.com/ClickHouse/ClickHouse/pull/5710) ([filimonov](https://github.com/filimonov))

#### Experimental Feature {#experimental-feature-2}

-   Input and output data format `Template`. It allows to specify custom format string for input and output. [#4354](https://github.com/ClickHouse/ClickHouse/issues/4354) [#6727](https://github.com/ClickHouse/ClickHouse/pull/6727) ([tavplubix](https://github.com/tavplubix))
-   Implementation of `LIVE VIEW` tables that were originally proposed in [#2898](https://github.com/ClickHouse/ClickHouse/pull/2898), prepared in [#3925](https://github.com/ClickHouse/ClickHouse/issues/3925), and then updated in [#5541](https://github.com/ClickHouse/ClickHouse/issues/5541). See [#5541](https://github.com/ClickHouse/ClickHouse/issues/5541) for detailed description. [#5541](https://github.com/ClickHouse/ClickHouse/issues/5541) ([vzakaznikov](https://github.com/vzakaznikov)) [#6425](https://github.com/ClickHouse/ClickHouse/pull/6425) ([Nikolai Kochetov](https://github.com/KochetovNicolai)) [#6656](https://github.com/ClickHouse/ClickHouse/pull/6656) ([vzakaznikov](https://github.com/vzakaznikov)) Note that `LIVE VIEW` feature may be removed in next versions.

#### Bug Fix {#bug-fix-8}

-   This release also contains all bug fixes from 19.13 and 19.11.
-   Fix segmentation fault when the table has skip indices and vertical merge happens. [#6723](https://github.com/ClickHouse/ClickHouse/pull/6723) ([alesapin](https://github.com/alesapin))
-   Fix per-column TTL with non-trivial column defaults. Previously in case of force TTL merge with `OPTIMIZE ... FINAL` query, expired values was replaced by type defaults instead of user-specified column defaults. [#6796](https://github.com/ClickHouse/ClickHouse/pull/6796) ([Anton Popov](https://github.com/CurtizJ))
-   Fix Kafka messages duplication problem on normal server restart. [#6597](https://github.com/ClickHouse/ClickHouse/pull/6597) ([Ivan](https://github.com/abyss7))
-   Fixed infinite loop when reading Kafka messages. Do not pause/resume consumer on subscription at all - otherwise it may get paused indefinitely in some scenarios. [#6354](https://github.com/ClickHouse/ClickHouse/pull/6354) ([Ivan](https://github.com/abyss7))
-   Fix `Key expression contains comparison between inconvertible types` exception in `bitmapContains` function. [#6136](https://github.com/ClickHouse/ClickHouse/issues/6136) [#6146](https://github.com/ClickHouse/ClickHouse/issues/6146) [#6156](https://github.com/ClickHouse/ClickHouse/pull/6156) ([dimarub2000](https://github.com/dimarub2000))
-   Fix segfault with enabled `optimize_skip_unused_shards` and missing sharding key. [#6384](https://github.com/ClickHouse/ClickHouse/pull/6384) ([Anton Popov](https://github.com/CurtizJ))
-   Fixed wrong code in mutations that may lead to memory corruption. Fixed segfault with read of address `0x14c0` that may happed due to concurrent `DROP TABLE` and `SELECT` from `system.parts` or `system.parts_columns`. Fixed race condition in preparation of mutation queries. Fixed deadlock caused by `OPTIMIZE` of Replicated tables and concurrent modification operations like ALTERs. [#6514](https://github.com/ClickHouse/ClickHouse/pull/6514) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Removed extra verbose logging in MySQL interface [#6389](https://github.com/ClickHouse/ClickHouse/pull/6389) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Return the ability to parse boolean settings from ‘true’ and ‘false’ in the configuration file. [#6278](https://github.com/ClickHouse/ClickHouse/pull/6278) ([alesapin](https://github.com/alesapin))
-   Fix crash in `quantile` and `median` function over `Nullable(Decimal128)`. [#6378](https://github.com/ClickHouse/ClickHouse/pull/6378) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed possible incomplete result returned by `SELECT` query with `WHERE` condition on primary key contained conversion to Float type. It was caused by incorrect checking of monotonicity in `toFloat` function. [#6248](https://github.com/ClickHouse/ClickHouse/issues/6248) [#6374](https://github.com/ClickHouse/ClickHouse/pull/6374) ([dimarub2000](https://github.com/dimarub2000))
-   Check `max_expanded_ast_elements` setting for mutations. Clear mutations after `TRUNCATE TABLE`. [#6205](https://github.com/ClickHouse/ClickHouse/pull/6205) ([Winter Zhang](https://github.com/zhang2014))
-   Fix JOIN results for key columns when used with `join_use_nulls`. Attach Nulls instead of columns defaults. [#6249](https://github.com/ClickHouse/ClickHouse/pull/6249) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix for skip indices with vertical merge and alter. Fix for `Bad size of marks file` exception. [#6594](https://github.com/ClickHouse/ClickHouse/issues/6594) [#6713](https://github.com/ClickHouse/ClickHouse/pull/6713) ([alesapin](https://github.com/alesapin))
-   Fix rare crash in `ALTER MODIFY COLUMN` and vertical merge when one of merged/altered parts is empty (0 rows) [#6746](https://github.com/ClickHouse/ClickHouse/issues/6746) [#6780](https://github.com/ClickHouse/ClickHouse/pull/6780) ([alesapin](https://github.com/alesapin))
-   Fixed bug in conversion of `LowCardinality` types in `AggregateFunctionFactory`. This fixes [#6257](https://github.com/ClickHouse/ClickHouse/issues/6257). [#6281](https://github.com/ClickHouse/ClickHouse/pull/6281) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix wrong behavior and possible segfaults in `topK` and `topKWeighted` aggregated functions. [#6404](https://github.com/ClickHouse/ClickHouse/pull/6404) ([Anton Popov](https://github.com/CurtizJ))
-   Fixed unsafe code around `getIdentifier` function. [#6401](https://github.com/ClickHouse/ClickHouse/issues/6401) [#6409](https://github.com/ClickHouse/ClickHouse/pull/6409) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed bug in MySQL wire protocol (is used while connecting to ClickHouse form MySQL client). Caused by heap buffer overflow in `PacketPayloadWriteBuffer`. [#6212](https://github.com/ClickHouse/ClickHouse/pull/6212) ([Yuriy Baranov](https://github.com/yurriy))
-   Fixed memory leak in `bitmapSubsetInRange` function. [#6819](https://github.com/ClickHouse/ClickHouse/pull/6819) ([Zhichang Yu](https://github.com/yuzhichang))
-   Fix rare bug when mutation executed after granularity change. [#6816](https://github.com/ClickHouse/ClickHouse/pull/6816) ([alesapin](https://github.com/alesapin))
-   Allow protobuf message with all fields by default. [#6132](https://github.com/ClickHouse/ClickHouse/pull/6132) ([Vitaly Baranov](https://github.com/vitlibar))
-   Resolve a bug with `nullIf` function when we send a `NULL` argument on the second argument. [#6446](https://github.com/ClickHouse/ClickHouse/pull/6446) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Fix rare bug with wrong memory allocation/deallocation in complex key cache dictionaries with string fields which leads to infinite memory consumption (looks like memory leak). Bug reproduces when string size was a power of two starting from eight (8, 16, 32, etc). [#6447](https://github.com/ClickHouse/ClickHouse/pull/6447) ([alesapin](https://github.com/alesapin))
-   Fixed Gorilla encoding on small sequences which caused exception `Cannot write after end of buffer`. [#6398](https://github.com/ClickHouse/ClickHouse/issues/6398) [#6444](https://github.com/ClickHouse/ClickHouse/pull/6444) ([Vasily Nemkov](https://github.com/Enmk))
-   Allow to use not nullable types in JOINs with `join_use_nulls` enabled. [#6705](https://github.com/ClickHouse/ClickHouse/pull/6705) ([Artem Zuikov](https://github.com/4ertus2))
-   Disable `Poco::AbstractConfiguration` substitutions in query in `clickhouse-client`. [#6706](https://github.com/ClickHouse/ClickHouse/pull/6706) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Avoid deadlock in `REPLACE PARTITION`. [#6677](https://github.com/ClickHouse/ClickHouse/pull/6677) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Using `arrayReduce` for constant arguments may lead to segfault. [#6242](https://github.com/ClickHouse/ClickHouse/issues/6242) [#6326](https://github.com/ClickHouse/ClickHouse/pull/6326) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix inconsistent parts which can appear if replica was restored after `DROP PARTITION`. [#6522](https://github.com/ClickHouse/ClickHouse/issues/6522) [#6523](https://github.com/ClickHouse/ClickHouse/pull/6523) ([tavplubix](https://github.com/tavplubix))
-   Fixed hang in `JSONExtractRaw` function. [#6195](https://github.com/ClickHouse/ClickHouse/issues/6195) [#6198](https://github.com/ClickHouse/ClickHouse/pull/6198) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix bug with incorrect skip indices serialization and aggregation with adaptive granularity. [#6594](https://github.com/ClickHouse/ClickHouse/issues/6594). [#6748](https://github.com/ClickHouse/ClickHouse/pull/6748) ([alesapin](https://github.com/alesapin))
-   Fix `WITH ROLLUP` and `WITH CUBE` modifiers of `GROUP BY` with two-level aggregation. [#6225](https://github.com/ClickHouse/ClickHouse/pull/6225) ([Anton Popov](https://github.com/CurtizJ))
-   Fix bug with writing secondary indices marks with adaptive granularity. [#6126](https://github.com/ClickHouse/ClickHouse/pull/6126) ([alesapin](https://github.com/alesapin))
-   Fix initialization order while server startup. Since `StorageMergeTree::background_task_handle` is initialized in `startup()` the `MergeTreeBlockOutputStream::write()` may try to use it before initialization. Just check if it is initialized. [#6080](https://github.com/ClickHouse/ClickHouse/pull/6080) ([Ivan](https://github.com/abyss7))
-   Clearing the data buffer from the previous read operation that was completed with an error. [#6026](https://github.com/ClickHouse/ClickHouse/pull/6026) ([Nikolay](https://github.com/bopohaa))
-   Fix bug with enabling adaptive granularity when creating a new replica for Replicated\*MergeTree table. [#6394](https://github.com/ClickHouse/ClickHouse/issues/6394) [#6452](https://github.com/ClickHouse/ClickHouse/pull/6452) ([alesapin](https://github.com/alesapin))
-   Fixed possible crash during server startup in case of exception happened in `libunwind` during exception at access to uninitialized `ThreadStatus` structure. [#6456](https://github.com/ClickHouse/ClickHouse/pull/6456) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov))
-   Fix crash in `yandexConsistentHash` function. Found by fuzz test. [#6304](https://github.com/ClickHouse/ClickHouse/issues/6304) [#6305](https://github.com/ClickHouse/ClickHouse/pull/6305) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed the possibility of hanging queries when server is overloaded and global thread pool becomes near full. This have higher chance to happen on clusters with large number of shards (hundreds), because distributed queries allocate a thread per connection to each shard. For example, this issue may reproduce if a cluster of 330 shards is processing 30 concurrent distributed queries. This issue affects all versions starting from 19.2. [#6301](https://github.com/ClickHouse/ClickHouse/pull/6301) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed logic of `arrayEnumerateUniqRanked` function. [#6423](https://github.com/ClickHouse/ClickHouse/pull/6423) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix segfault when decoding symbol table. [#6603](https://github.com/ClickHouse/ClickHouse/pull/6603) ([Amos Bird](https://github.com/amosbird))
-   Fixed irrelevant exception in cast of `LowCardinality(Nullable)` to not-Nullable column in case if it does not contain Nulls (e.g. in query like `SELECT CAST(CAST('Hello' AS LowCardinality(Nullable(String))) AS String)`. [#6094](https://github.com/ClickHouse/ClickHouse/issues/6094) [#6119](https://github.com/ClickHouse/ClickHouse/pull/6119) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Removed extra quoting of description in `system.settings` table. [#6696](https://github.com/ClickHouse/ClickHouse/issues/6696) [#6699](https://github.com/ClickHouse/ClickHouse/pull/6699) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Avoid possible deadlock in `TRUNCATE` of Replicated table. [#6695](https://github.com/ClickHouse/ClickHouse/pull/6695) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix reading in order of sorting key. [#6189](https://github.com/ClickHouse/ClickHouse/pull/6189) ([Anton Popov](https://github.com/CurtizJ))
-   Fix `ALTER TABLE ... UPDATE` query for tables with `enable_mixed_granularity_parts=1`. [#6543](https://github.com/ClickHouse/ClickHouse/pull/6543) ([alesapin](https://github.com/alesapin))
-   Fix bug opened by [#4405](https://github.com/ClickHouse/ClickHouse/pull/4405) (since 19.4.0). Reproduces in queries to Distributed tables over MergeTree tables when we does not query any columns (`SELECT 1`). [#6236](https://github.com/ClickHouse/ClickHouse/pull/6236) ([alesapin](https://github.com/alesapin))
-   Fixed overflow in integer division of signed type to unsigned type. The behaviour was exactly as in C or C++ language (integer promotion rules) that may be surprising. Please note that the overflow is still possible when dividing large signed number to large unsigned number or vice-versa (but that case is less usual). The issue existed in all server versions. [#6214](https://github.com/ClickHouse/ClickHouse/issues/6214) [#6233](https://github.com/ClickHouse/ClickHouse/pull/6233) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Limit maximum sleep time for throttling when `max_execution_speed` or `max_execution_speed_bytes` is set. Fixed false errors like `Estimated query execution time (inf seconds) is too long`. [#5547](https://github.com/ClickHouse/ClickHouse/issues/5547) [#6232](https://github.com/ClickHouse/ClickHouse/pull/6232) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed issues about using `MATERIALIZED` columns and aliases in `MaterializedView`. [#448](https://github.com/ClickHouse/ClickHouse/issues/448) [#3484](https://github.com/ClickHouse/ClickHouse/issues/3484) [#3450](https://github.com/ClickHouse/ClickHouse/issues/3450) [#2878](https://github.com/ClickHouse/ClickHouse/issues/2878) [#2285](https://github.com/ClickHouse/ClickHouse/issues/2285) [#3796](https://github.com/ClickHouse/ClickHouse/pull/3796) ([Amos Bird](https://github.com/amosbird)) [#6316](https://github.com/ClickHouse/ClickHouse/pull/6316) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix `FormatFactory` behaviour for input streams which are not implemented as processor. [#6495](https://github.com/ClickHouse/ClickHouse/pull/6495) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed typo. [#6631](https://github.com/ClickHouse/ClickHouse/pull/6631) ([Alex Ryndin](https://github.com/alexryndin))
-   Typo in the error message ( is -\> are ). [#6839](https://github.com/ClickHouse/ClickHouse/pull/6839) ([Denis Zhuravlev](https://github.com/den-crane))
-   Fixed error while parsing of columns list from string if type contained a comma (this issue was relevant for `File`, `URL`, `HDFS` storages) [#6217](https://github.com/ClickHouse/ClickHouse/issues/6217). [#6209](https://github.com/ClickHouse/ClickHouse/pull/6209) ([dimarub2000](https://github.com/dimarub2000))

#### Security Fix {#security-fix}

-   This release also contains all bug security fixes from 19.13 and 19.11.
-   Fixed the possibility of a fabricated query to cause server crash due to stack overflow in SQL parser. Fixed the possibility of stack overflow in Merge and Distributed tables, materialized views and conditions for row-level security that involve subqueries. [#6433](https://github.com/ClickHouse/ClickHouse/pull/6433) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Improvement {#improvement-3}

-   Correct implementation of ternary logic for `AND/OR`. [#6048](https://github.com/ClickHouse/ClickHouse/pull/6048) ([Alexander Kazakov](https://github.com/Akazz))
-   Now values and rows with expired TTL will be removed after `OPTIMIZE ... FINAL` query from old parts without TTL infos or with outdated TTL infos, e.g. after `ALTER ... MODIFY TTL` query. Added queries `SYSTEM STOP/START TTL MERGES` to disallow/allow assign merges with TTL and filter expired values in all merges. [#6274](https://github.com/ClickHouse/ClickHouse/pull/6274) ([Anton Popov](https://github.com/CurtizJ))
-   Possibility to change the location of ClickHouse history file for client using `CLICKHOUSE_HISTORY_FILE` env. [#6840](https://github.com/ClickHouse/ClickHouse/pull/6840) ([filimonov](https://github.com/filimonov))
-   Remove `dry_run` flag from `InterpreterSelectQuery`. … [#6375](https://github.com/ClickHouse/ClickHouse/pull/6375) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Support `ASOF JOIN` with `ON` section. [#6211](https://github.com/ClickHouse/ClickHouse/pull/6211) ([Artem Zuikov](https://github.com/4ertus2))
-   Better support of skip indexes for mutations and replication. Support for `MATERIALIZE/CLEAR INDEX ... IN PARTITION` query. `UPDATE x = x` recalculates all indices that use column `x`. [#5053](https://github.com/ClickHouse/ClickHouse/pull/5053) ([Nikita Vasilev](https://github.com/nikvas0))
-   Allow to `ATTACH` live views (for example, at the server startup) regardless to `allow_experimental_live_view` setting. [#6754](https://github.com/ClickHouse/ClickHouse/pull/6754) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   For stack traces gathered by query profiler, do not include stack frames generated by the query profiler itself. [#6250](https://github.com/ClickHouse/ClickHouse/pull/6250) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Now table functions `values`, `file`, `url`, `hdfs` have support for ALIAS columns. [#6255](https://github.com/ClickHouse/ClickHouse/pull/6255) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Throw an exception if `config.d` file does not have the corresponding root element as the config file. [#6123](https://github.com/ClickHouse/ClickHouse/pull/6123) ([dimarub2000](https://github.com/dimarub2000))
-   Print extra info in exception message for `no space left on device`. [#6182](https://github.com/ClickHouse/ClickHouse/issues/6182), [#6252](https://github.com/ClickHouse/ClickHouse/issues/6252) [#6352](https://github.com/ClickHouse/ClickHouse/pull/6352) ([tavplubix](https://github.com/tavplubix))
-   When determining shards of a `Distributed` table to be covered by a read query (for `optimize_skip_unused_shards` = 1) ClickHouse now checks conditions from both `prewhere` and `where` clauses of select statement. [#6521](https://github.com/ClickHouse/ClickHouse/pull/6521) ([Alexander Kazakov](https://github.com/Akazz))
-   Enabled `SIMDJSON` for machines without AVX2 but with SSE 4.2 and PCLMUL instruction set. [#6285](https://github.com/ClickHouse/ClickHouse/issues/6285) [#6320](https://github.com/ClickHouse/ClickHouse/pull/6320) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   ClickHouse can work on filesystems without `O_DIRECT` support (such as ZFS and BtrFS) without additional tuning. [#4449](https://github.com/ClickHouse/ClickHouse/issues/4449) [#6730](https://github.com/ClickHouse/ClickHouse/pull/6730) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Support push down predicate for final subquery. [#6120](https://github.com/ClickHouse/ClickHouse/pull/6120) ([TCeason](https://github.com/TCeason)) [#6162](https://github.com/ClickHouse/ClickHouse/pull/6162) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Better `JOIN ON` keys extraction [#6131](https://github.com/ClickHouse/ClickHouse/pull/6131) ([Artem Zuikov](https://github.com/4ertus2))
-   Upated `SIMDJSON`. [#6285](https://github.com/ClickHouse/ClickHouse/issues/6285). [#6306](https://github.com/ClickHouse/ClickHouse/pull/6306) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Optimize selecting of smallest column for `SELECT count()` query. [#6344](https://github.com/ClickHouse/ClickHouse/pull/6344) ([Amos Bird](https://github.com/amosbird))
-   Added `strict` parameter in `windowFunnel()`. When the `strict` is set, the `windowFunnel()` applies conditions only for the unique values. [#6548](https://github.com/ClickHouse/ClickHouse/pull/6548) ([achimbab](https://github.com/achimbab))
-   Safer interface of `mysqlxx::Pool`. [#6150](https://github.com/ClickHouse/ClickHouse/pull/6150) ([avasiliev](https://github.com/avasiliev))
-   Options line size when executing with `--help` option now corresponds with terminal size. [#6590](https://github.com/ClickHouse/ClickHouse/pull/6590) ([dimarub2000](https://github.com/dimarub2000))
-   Disable “read in order” optimization for aggregation without keys. [#6599](https://github.com/ClickHouse/ClickHouse/pull/6599) ([Anton Popov](https://github.com/CurtizJ))
-   HTTP status code for `INCORRECT_DATA` and `TYPE_MISMATCH` error codes was changed from default `500 Internal Server Error` to `400 Bad Request`. [#6271](https://github.com/ClickHouse/ClickHouse/pull/6271) ([Alexander Rodin](https://github.com/a-rodin))
-   Move Join object from `ExpressionAction` into `AnalyzedJoin`. `ExpressionAnalyzer` and `ExpressionAction` do not know about `Join` class anymore. Its logic is hidden by `AnalyzedJoin` iface. [#6801](https://github.com/ClickHouse/ClickHouse/pull/6801) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed possible deadlock of distributed queries when one of shards is localhost but the query is sent via network connection. [#6759](https://github.com/ClickHouse/ClickHouse/pull/6759) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Changed semantic of multiple tables `RENAME` to avoid possible deadlocks. [#6757](https://github.com/ClickHouse/ClickHouse/issues/6757). [#6756](https://github.com/ClickHouse/ClickHouse/pull/6756) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Rewritten MySQL compatibility server to prevent loading full packet payload in memory. Decreased memory consumption for each connection to approximately `2 * DBMS_DEFAULT_BUFFER_SIZE` (read/write buffers). [#5811](https://github.com/ClickHouse/ClickHouse/pull/5811) ([Yuriy Baranov](https://github.com/yurriy))
-   Move AST alias interpreting logic out of parser that does not have to know anything about query semantics. [#6108](https://github.com/ClickHouse/ClickHouse/pull/6108) ([Artem Zuikov](https://github.com/4ertus2))
-   Slightly more safe parsing of `NamesAndTypesList`. [#6408](https://github.com/ClickHouse/ClickHouse/issues/6408). [#6410](https://github.com/ClickHouse/ClickHouse/pull/6410) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `clickhouse-copier`: Allow use `where_condition` from config with `partition_key` alias in query for checking partition existence (Earlier it was used only in reading data queries). [#6577](https://github.com/ClickHouse/ClickHouse/pull/6577) ([proller](https://github.com/proller))
-   Added optional message argument in `throwIf`. ([#5772](https://github.com/ClickHouse/ClickHouse/issues/5772)) [#6329](https://github.com/ClickHouse/ClickHouse/pull/6329) ([Vdimir](https://github.com/Vdimir))
-   Server exception got while sending insertion data is now being processed in client as well. [#5891](https://github.com/ClickHouse/ClickHouse/issues/5891) [#6711](https://github.com/ClickHouse/ClickHouse/pull/6711) ([dimarub2000](https://github.com/dimarub2000))
-   Added a metric `DistributedFilesToInsert` that shows the total number of files in filesystem that are selected to send to remote servers by Distributed tables. The number is summed across all shards. [#6600](https://github.com/ClickHouse/ClickHouse/pull/6600) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Move most of JOINs prepare logic from `ExpressionAction/ExpressionAnalyzer` to `AnalyzedJoin`. [#6785](https://github.com/ClickHouse/ClickHouse/pull/6785) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix TSan [warning](https://clickhouse-test-reports.s3.yandex.net/6399/c1c1d1daa98e199e620766f1bd06a5921050a00d/functional_stateful_tests_(thread).html) ‘lock-order-inversion’. [#6740](https://github.com/ClickHouse/ClickHouse/pull/6740) ([Vasily Nemkov](https://github.com/Enmk))
-   Better information messages about lack of Linux capabilities. Logging fatal errors with “fatal” level, that will make it easier to find in `system.text_log`. [#6441](https://github.com/ClickHouse/ClickHouse/pull/6441) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   When enable dumping temporary data to the disk to restrict memory usage during `GROUP BY`, `ORDER BY`, it didn’t check the free disk space. The fix add a new setting `min_free_disk_space`, when the free disk space it smaller then the threshold, the query will stop and throw `ErrorCodes::NOT_ENOUGH_SPACE`. [#6678](https://github.com/ClickHouse/ClickHouse/pull/6678) ([Weiqing Xu](https://github.com/weiqxu)) [#6691](https://github.com/ClickHouse/ClickHouse/pull/6691) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Removed recursive rwlock by thread. It makes no sense, because threads are reused between queries. `SELECT` query may acquire a lock in one thread, hold a lock from another thread and exit from first thread. In the same time, first thread can be reused by `DROP` query. This will lead to false “Attempt to acquire exclusive lock recursively” messages. [#6771](https://github.com/ClickHouse/ClickHouse/pull/6771) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Split `ExpressionAnalyzer.appendJoin()`. Prepare a place in `ExpressionAnalyzer` for `MergeJoin`. [#6524](https://github.com/ClickHouse/ClickHouse/pull/6524) ([Artem Zuikov](https://github.com/4ertus2))
-   Added `mysql_native_password` authentication plugin to MySQL compatibility server. [#6194](https://github.com/ClickHouse/ClickHouse/pull/6194) ([Yuriy Baranov](https://github.com/yurriy))
-   Less number of `clock_gettime` calls; fixed ABI compatibility between debug/release in `Allocator` (insignificant issue). [#6197](https://github.com/ClickHouse/ClickHouse/pull/6197) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Move `collectUsedColumns` from `ExpressionAnalyzer` to `SyntaxAnalyzer`. `SyntaxAnalyzer` makes `required_source_columns` itself now. [#6416](https://github.com/ClickHouse/ClickHouse/pull/6416) ([Artem Zuikov](https://github.com/4ertus2))
-   Add setting `joined_subquery_requires_alias` to require aliases for subselects and table functions in `FROM` that more than one table is present (i.e. queries with JOINs). [#6733](https://github.com/ClickHouse/ClickHouse/pull/6733) ([Artem Zuikov](https://github.com/4ertus2))
-   Extract `GetAggregatesVisitor` class from `ExpressionAnalyzer`. [#6458](https://github.com/ClickHouse/ClickHouse/pull/6458) ([Artem Zuikov](https://github.com/4ertus2))
-   `system.query_log`: change data type of `type` column to `Enum`. [#6265](https://github.com/ClickHouse/ClickHouse/pull/6265) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov))
-   Static linking of `sha256_password` authentication plugin. [#6512](https://github.com/ClickHouse/ClickHouse/pull/6512) ([Yuriy Baranov](https://github.com/yurriy))
-   Avoid extra dependency for the setting `compile` to work. In previous versions, the user may get error like `cannot open crti.o`, `unable to find library -lc` etc. [#6309](https://github.com/ClickHouse/ClickHouse/pull/6309) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   More validation of the input that may come from malicious replica. [#6303](https://github.com/ClickHouse/ClickHouse/pull/6303) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Now `clickhouse-obfuscator` file is available in `clickhouse-client` package. In previous versions it was available as `clickhouse obfuscator` (with whitespace). [#5816](https://github.com/ClickHouse/ClickHouse/issues/5816) [#6609](https://github.com/ClickHouse/ClickHouse/pull/6609) ([dimarub2000](https://github.com/dimarub2000))
-   Fixed deadlock when we have at least two queries that read at least two tables in different order and another query that performs DDL operation on one of tables. Fixed another very rare deadlock. [#6764](https://github.com/ClickHouse/ClickHouse/pull/6764) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added `os_thread_ids` column to `system.processes` and `system.query_log` for better debugging possibilities. [#6763](https://github.com/ClickHouse/ClickHouse/pull/6763) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   A workaround for PHP mysqlnd extension bugs which occur when `sha256_password` is used as a default authentication plugin (described in [#6031](https://github.com/ClickHouse/ClickHouse/issues/6031)). [#6113](https://github.com/ClickHouse/ClickHouse/pull/6113) ([Yuriy Baranov](https://github.com/yurriy))
-   Remove unneeded place with changed nullability columns. [#6693](https://github.com/ClickHouse/ClickHouse/pull/6693) ([Artem Zuikov](https://github.com/4ertus2))
-   Set default value of `queue_max_wait_ms` to zero, because current value (five seconds) makes no sense. There are rare circumstances when this settings has any use. Added settings `replace_running_query_max_wait_ms`, `kafka_max_wait_ms` and `connection_pool_max_wait_ms` for disambiguation. [#6692](https://github.com/ClickHouse/ClickHouse/pull/6692) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Extract `SelectQueryExpressionAnalyzer` from `ExpressionAnalyzer`. Keep the last one for non-select queries. [#6499](https://github.com/ClickHouse/ClickHouse/pull/6499) ([Artem Zuikov](https://github.com/4ertus2))
-   Removed duplicating input and output formats. [#6239](https://github.com/ClickHouse/ClickHouse/pull/6239) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Allow user to override `poll_interval` and `idle_connection_timeout` settings on connection. [#6230](https://github.com/ClickHouse/ClickHouse/pull/6230) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `MergeTree` now has an additional option `ttl_only_drop_parts` (disabled by default) to avoid partial pruning of parts, so that they dropped completely when all the rows in a part are expired. [#6191](https://github.com/ClickHouse/ClickHouse/pull/6191) ([Sergi Vladykin](https://github.com/svladykin))
-   Type checks for set index functions. Throw exception if function got a wrong type. This fixes fuzz test with UBSan. [#6511](https://github.com/ClickHouse/ClickHouse/pull/6511) ([Nikita Vasilev](https://github.com/nikvas0))

#### Performance Improvement {#performance-improvement-2}

-   Optimize queries with `ORDER BY expressions` clause, where `expressions` have coinciding prefix with sorting key in `MergeTree` tables. This optimization is controlled by `optimize_read_in_order` setting. [#6054](https://github.com/ClickHouse/ClickHouse/pull/6054) [#6629](https://github.com/ClickHouse/ClickHouse/pull/6629) ([Anton Popov](https://github.com/CurtizJ))
-   Allow to use multiple threads during parts loading and removal. [#6372](https://github.com/ClickHouse/ClickHouse/issues/6372) [#6074](https://github.com/ClickHouse/ClickHouse/issues/6074) [#6438](https://github.com/ClickHouse/ClickHouse/pull/6438) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Implemented batch variant of updating aggregate function states. It may lead to performance benefits. [#6435](https://github.com/ClickHouse/ClickHouse/pull/6435) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Using `FastOps` library for functions `exp`, `log`, `sigmoid`, `tanh`. FastOps is a fast vector math library from Michael Parakhin (Yandex CTO). Improved performance of `exp` and `log` functions more than 6 times. The functions `exp` and `log` from `Float32` argument will return `Float32` (in previous versions they always return `Float64`). Now `exp(nan)` may return `inf`. The result of `exp` and `log` functions may be not the nearest machine representable number to the true answer. [#6254](https://github.com/ClickHouse/ClickHouse/pull/6254) ([alexey-milovidov](https://github.com/alexey-milovidov)) Using Danila Kutenin variant to make fastops working [#6317](https://github.com/ClickHouse/ClickHouse/pull/6317) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Disable consecutive key optimization for `UInt8/16`. [#6298](https://github.com/ClickHouse/ClickHouse/pull/6298) [#6701](https://github.com/ClickHouse/ClickHouse/pull/6701) ([akuzm](https://github.com/akuzm))
-   Improved performance of `simdjson` library by getting rid of dynamic allocation in `ParsedJson::Iterator`. [#6479](https://github.com/ClickHouse/ClickHouse/pull/6479) ([Vitaly Baranov](https://github.com/vitlibar))
-   Pre-fault pages when allocating memory with `mmap()`. [#6667](https://github.com/ClickHouse/ClickHouse/pull/6667) ([akuzm](https://github.com/akuzm))
-   Fix performance bug in `Decimal` comparison. [#6380](https://github.com/ClickHouse/ClickHouse/pull/6380) ([Artem Zuikov](https://github.com/4ertus2))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-4}

-   Remove Compiler (runtime template instantiation) because we’ve win over it’s performance. [#6646](https://github.com/ClickHouse/ClickHouse/pull/6646) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added performance test to show degradation of performance in gcc-9 in more isolated way. [#6302](https://github.com/ClickHouse/ClickHouse/pull/6302) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added table function `numbers_mt`, which is multithreaded version of `numbers`. Updated performance tests with hash functions. [#6554](https://github.com/ClickHouse/ClickHouse/pull/6554) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Comparison mode in `clickhouse-benchmark` [#6220](https://github.com/ClickHouse/ClickHouse/issues/6220) [#6343](https://github.com/ClickHouse/ClickHouse/pull/6343) ([dimarub2000](https://github.com/dimarub2000))
-   Best effort for printing stack traces. Also added `SIGPROF` as a debugging signal to print stack trace of a running thread. [#6529](https://github.com/ClickHouse/ClickHouse/pull/6529) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Every function in its own file, part 10. [#6321](https://github.com/ClickHouse/ClickHouse/pull/6321) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Remove doubled const `TABLE_IS_READ_ONLY`. [#6566](https://github.com/ClickHouse/ClickHouse/pull/6566) ([filimonov](https://github.com/filimonov))
-   Formatting changes for `StringHashMap` PR [#5417](https://github.com/ClickHouse/ClickHouse/issues/5417). [#6700](https://github.com/ClickHouse/ClickHouse/pull/6700) ([akuzm](https://github.com/akuzm))
-   Better subquery for join creation in `ExpressionAnalyzer`. [#6824](https://github.com/ClickHouse/ClickHouse/pull/6824) ([Artem Zuikov](https://github.com/4ertus2))
-   Remove a redundant condition (found by PVS Studio). [#6775](https://github.com/ClickHouse/ClickHouse/pull/6775) ([akuzm](https://github.com/akuzm))
-   Separate the hash table interface for `ReverseIndex`. [#6672](https://github.com/ClickHouse/ClickHouse/pull/6672) ([akuzm](https://github.com/akuzm))
-   Refactoring of settings. [#6689](https://github.com/ClickHouse/ClickHouse/pull/6689) ([alesapin](https://github.com/alesapin))
-   Add comments for `set` index functions. [#6319](https://github.com/ClickHouse/ClickHouse/pull/6319) ([Nikita Vasilev](https://github.com/nikvas0))
-   Increase OOM score in debug version on Linux. [#6152](https://github.com/ClickHouse/ClickHouse/pull/6152) ([akuzm](https://github.com/akuzm))
-   HDFS HA now work in debug build. [#6650](https://github.com/ClickHouse/ClickHouse/pull/6650) ([Weiqing Xu](https://github.com/weiqxu))
-   Added a test to `transform_query_for_external_database`. [#6388](https://github.com/ClickHouse/ClickHouse/pull/6388) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add test for multiple materialized views for Kafka table. [#6509](https://github.com/ClickHouse/ClickHouse/pull/6509) ([Ivan](https://github.com/abyss7))
-   Make a better build scheme. [#6500](https://github.com/ClickHouse/ClickHouse/pull/6500) ([Ivan](https://github.com/abyss7))
-   Fixed `test_external_dictionaries` integration in case it was executed under non root user. [#6507](https://github.com/ClickHouse/ClickHouse/pull/6507) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   The bug reproduces when total size of written packets exceeds `DBMS_DEFAULT_BUFFER_SIZE`. [#6204](https://github.com/ClickHouse/ClickHouse/pull/6204) ([Yuriy Baranov](https://github.com/yurriy))
-   Added a test for `RENAME` table race condition [#6752](https://github.com/ClickHouse/ClickHouse/pull/6752) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Avoid data race on Settings in `KILL QUERY`. [#6753](https://github.com/ClickHouse/ClickHouse/pull/6753) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add integration test for handling errors by a cache dictionary. [#6755](https://github.com/ClickHouse/ClickHouse/pull/6755) ([Vitaly Baranov](https://github.com/vitlibar))
-   Disable parsing of ELF object files on Mac OS, because it makes no sense. [#6578](https://github.com/ClickHouse/ClickHouse/pull/6578) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Attempt to make changelog generator better. [#6327](https://github.com/ClickHouse/ClickHouse/pull/6327) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Adding `-Wshadow` switch to the GCC. [#6325](https://github.com/ClickHouse/ClickHouse/pull/6325) ([kreuzerkrieg](https://github.com/kreuzerkrieg))
-   Removed obsolete code for `mimalloc` support. [#6715](https://github.com/ClickHouse/ClickHouse/pull/6715) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `zlib-ng` determines x86 capabilities and saves this info to global variables. This is done in defalteInit call, which may be made by different threads simultaneously. To avoid multithreaded writes, do it on library startup. [#6141](https://github.com/ClickHouse/ClickHouse/pull/6141) ([akuzm](https://github.com/akuzm))
-   Regression test for a bug which in join which was fixed in [#5192](https://github.com/ClickHouse/ClickHouse/issues/5192). [#6147](https://github.com/ClickHouse/ClickHouse/pull/6147) ([Bakhtiyor Ruziev](https://github.com/theruziev))
-   Fixed MSan report. [#6144](https://github.com/ClickHouse/ClickHouse/pull/6144) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix flapping TTL test. [#6782](https://github.com/ClickHouse/ClickHouse/pull/6782) ([Anton Popov](https://github.com/CurtizJ))
-   Fixed false data race in `MergeTreeDataPart::is_frozen` field. [#6583](https://github.com/ClickHouse/ClickHouse/pull/6583) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed timeouts in fuzz test. In previous version, it managed to find false hangup in query `SELECT * FROM numbers_mt(gccMurmurHash(''))`. [#6582](https://github.com/ClickHouse/ClickHouse/pull/6582) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added debug checks to `static_cast` of columns. [#6581](https://github.com/ClickHouse/ClickHouse/pull/6581) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Support for Oracle Linux in official RPM packages. [#6356](https://github.com/ClickHouse/ClickHouse/issues/6356) [#6585](https://github.com/ClickHouse/ClickHouse/pull/6585) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Changed json perftests from `once` to `loop` type. [#6536](https://github.com/ClickHouse/ClickHouse/pull/6536) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   `odbc-bridge.cpp` defines `main()` so it should not be included in `clickhouse-lib`. [#6538](https://github.com/ClickHouse/ClickHouse/pull/6538) ([Orivej Desh](https://github.com/orivej))
-   Test for crash in `FULL|RIGHT JOIN` with nulls in right table’s keys. [#6362](https://github.com/ClickHouse/ClickHouse/pull/6362) ([Artem Zuikov](https://github.com/4ertus2))
-   Added a test for the limit on expansion of aliases just in case. [#6442](https://github.com/ClickHouse/ClickHouse/pull/6442) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Switched from `boost::filesystem` to `std::filesystem` where appropriate. [#6253](https://github.com/ClickHouse/ClickHouse/pull/6253) [#6385](https://github.com/ClickHouse/ClickHouse/pull/6385) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added RPM packages to website. [#6251](https://github.com/ClickHouse/ClickHouse/pull/6251) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add a test for fixed `Unknown identifier` exception in `IN` section. [#6708](https://github.com/ClickHouse/ClickHouse/pull/6708) ([Artem Zuikov](https://github.com/4ertus2))
-   Simplify `shared_ptr_helper` because people facing difficulties understanding it. [#6675](https://github.com/ClickHouse/ClickHouse/pull/6675) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added performance tests for fixed Gorilla and DoubleDelta codec. [#6179](https://github.com/ClickHouse/ClickHouse/pull/6179) ([Vasily Nemkov](https://github.com/Enmk))
-   Split the integration test `test_dictionaries` into 4 separate tests. [#6776](https://github.com/ClickHouse/ClickHouse/pull/6776) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix PVS-Studio warning in `PipelineExecutor`. [#6777](https://github.com/ClickHouse/ClickHouse/pull/6777) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Allow to use `library` dictionary source with ASan. [#6482](https://github.com/ClickHouse/ClickHouse/pull/6482) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added option to generate changelog from a list of PRs. [#6350](https://github.com/ClickHouse/ClickHouse/pull/6350) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Lock the `TinyLog` storage when reading. [#6226](https://github.com/ClickHouse/ClickHouse/pull/6226) ([akuzm](https://github.com/akuzm))
-   Check for broken symlinks in CI. [#6634](https://github.com/ClickHouse/ClickHouse/pull/6634) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Increase timeout for “stack overflow” test because it may take a long time in debug build. [#6637](https://github.com/ClickHouse/ClickHouse/pull/6637) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added a check for double whitespaces. [#6643](https://github.com/ClickHouse/ClickHouse/pull/6643) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix `new/delete` memory tracking when build with sanitizers. Tracking is not clear. It only prevents memory limit exceptions in tests. [#6450](https://github.com/ClickHouse/ClickHouse/pull/6450) ([Artem Zuikov](https://github.com/4ertus2))
-   Enable back the check of undefined symbols while linking. [#6453](https://github.com/ClickHouse/ClickHouse/pull/6453) ([Ivan](https://github.com/abyss7))
-   Avoid rebuilding `hyperscan` every day. [#6307](https://github.com/ClickHouse/ClickHouse/pull/6307) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed UBSan report in `ProtobufWriter`. [#6163](https://github.com/ClickHouse/ClickHouse/pull/6163) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Don’t allow to use query profiler with sanitizers because it is not compatible. [#6769](https://github.com/ClickHouse/ClickHouse/pull/6769) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add test for reloading a dictionary after fail by timer. [#6114](https://github.com/ClickHouse/ClickHouse/pull/6114) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix inconsistency in `PipelineExecutor::prepareProcessor` argument type. [#6494](https://github.com/ClickHouse/ClickHouse/pull/6494) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Added a test for bad URIs. [#6493](https://github.com/ClickHouse/ClickHouse/pull/6493) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added more checks to `CAST` function. This should get more information about segmentation fault in fuzzy test. [#6346](https://github.com/ClickHouse/ClickHouse/pull/6346) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Added `gcc-9` support to `docker/builder` container that builds image locally. [#6333](https://github.com/ClickHouse/ClickHouse/pull/6333) ([Gleb Novikov](https://github.com/NanoBjorn))
-   Test for primary key with `LowCardinality(String)`. [#5044](https://github.com/ClickHouse/ClickHouse/issues/5044) [#6219](https://github.com/ClickHouse/ClickHouse/pull/6219) ([dimarub2000](https://github.com/dimarub2000))
-   Fixed tests affected by slow stack traces printing. [#6315](https://github.com/ClickHouse/ClickHouse/pull/6315) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add a test case for crash in `groupUniqArray` fixed in [#6029](https://github.com/ClickHouse/ClickHouse/pull/6029). [#4402](https://github.com/ClickHouse/ClickHouse/issues/4402) [#6129](https://github.com/ClickHouse/ClickHouse/pull/6129) ([akuzm](https://github.com/akuzm))
-   Fixed indices mutations tests. [#6645](https://github.com/ClickHouse/ClickHouse/pull/6645) ([Nikita Vasilev](https://github.com/nikvas0))
-   In performance test, do not read query log for queries we didn’t run. [#6427](https://github.com/ClickHouse/ClickHouse/pull/6427) ([akuzm](https://github.com/akuzm))
-   Materialized view now could be created with any low cardinality types regardless to the setting about suspicious low cardinality types. [#6428](https://github.com/ClickHouse/ClickHouse/pull/6428) ([Olga Khvostikova](https://github.com/stavrolia))
-   Updated tests for `send_logs_level` setting. [#6207](https://github.com/ClickHouse/ClickHouse/pull/6207) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix build under gcc-8.2. [#6196](https://github.com/ClickHouse/ClickHouse/pull/6196) ([Max Akhmedov](https://github.com/zlobober))
-   Fix build with internal libc++. [#6724](https://github.com/ClickHouse/ClickHouse/pull/6724) ([Ivan](https://github.com/abyss7))
-   Fix shared build with `rdkafka` library [#6101](https://github.com/ClickHouse/ClickHouse/pull/6101) ([Ivan](https://github.com/abyss7))
-   Fixes for Mac OS build (incomplete). [#6390](https://github.com/ClickHouse/ClickHouse/pull/6390) ([alexey-milovidov](https://github.com/alexey-milovidov)) [#6429](https://github.com/ClickHouse/ClickHouse/pull/6429) ([alex-zaitsev](https://github.com/alex-zaitsev))
-   Fix “splitted” build. [#6618](https://github.com/ClickHouse/ClickHouse/pull/6618) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Other build fixes: [#6186](https://github.com/ClickHouse/ClickHouse/pull/6186) ([Amos Bird](https://github.com/amosbird)) [#6486](https://github.com/ClickHouse/ClickHouse/pull/6486) [#6348](https://github.com/ClickHouse/ClickHouse/pull/6348) ([vxider](https://github.com/Vxider)) [#6744](https://github.com/ClickHouse/ClickHouse/pull/6744) ([Ivan](https://github.com/abyss7)) [#6016](https://github.com/ClickHouse/ClickHouse/pull/6016) [#6421](https://github.com/ClickHouse/ClickHouse/pull/6421) [#6491](https://github.com/ClickHouse/ClickHouse/pull/6491) ([proller](https://github.com/proller))

#### Backward Incompatible Change {#backward-incompatible-change-3}

-   Removed rarely used table function `catBoostPool` and storage `CatBoostPool`. If you have used this table function, please write email to `clickhouse-feedback@yandex-team.com`. Note that CatBoost integration remains and will be supported. [#6279](https://github.com/ClickHouse/ClickHouse/pull/6279) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Disable `ANY RIGHT JOIN` and `ANY FULL JOIN` by default. Set `any_join_distinct_right_table_keys` setting to enable them. [#5126](https://github.com/ClickHouse/ClickHouse/issues/5126) [#6351](https://github.com/ClickHouse/ClickHouse/pull/6351) ([Artem Zuikov](https://github.com/4ertus2))

## ClickHouse Release 19.13 {#clickhouse-release-19-13}

### ClickHouse Release 19.13.6.51, 2019-10-02 {#clickhouse-release-19-13-6-51-2019-10-02}

#### Bug Fix {#bug-fix-9}

-   This release also contains all bug fixes from 19.11.12.69.

### ClickHouse Release 19.13.5.44, 2019-09-20 {#clickhouse-release-19-13-5-44-2019-09-20}

#### Bug Fix {#bug-fix-10}

-   This release also contains all bug fixes from 19.14.6.12.
-   Fixed possible inconsistent state of table while executing `DROP` query for replicated table while zookeeper is not accessible. [#6045](https://github.com/ClickHouse/ClickHouse/issues/6045) [#6413](https://github.com/ClickHouse/ClickHouse/pull/6413) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov))
-   Fix for data race in StorageMerge [#6717](https://github.com/ClickHouse/ClickHouse/pull/6717) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix bug introduced in query profiler which leads to endless recv from socket. [#6386](https://github.com/ClickHouse/ClickHouse/pull/6386) ([alesapin](https://github.com/alesapin))
-   Fix excessive CPU usage while executing `JSONExtractRaw` function over a boolean value. [#6208](https://github.com/ClickHouse/ClickHouse/pull/6208) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fixes the regression while pushing to materialized view. [#6415](https://github.com/ClickHouse/ClickHouse/pull/6415) ([Ivan](https://github.com/abyss7))
-   Table function `url` had the vulnerability allowed the attacker to inject arbitrary HTTP headers in the request. This issue was found by [Nikita Tikhomirov](https://github.com/NSTikhomirov). [#6466](https://github.com/ClickHouse/ClickHouse/pull/6466) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix useless `AST` check in Set index. [#6510](https://github.com/ClickHouse/ClickHouse/issues/6510) [#6651](https://github.com/ClickHouse/ClickHouse/pull/6651) ([Nikita Vasilev](https://github.com/nikvas0))
-   Fixed parsing of `AggregateFunction` values embedded in query. [#6575](https://github.com/ClickHouse/ClickHouse/issues/6575) [#6773](https://github.com/ClickHouse/ClickHouse/pull/6773) ([Zhichang Yu](https://github.com/yuzhichang))
-   Fixed wrong behaviour of `trim` functions family. [#6647](https://github.com/ClickHouse/ClickHouse/pull/6647) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.13.4.32, 2019-09-10 {#clickhouse-release-19-13-4-32-2019-09-10}

#### Bug Fix {#bug-fix-11}

-   This release also contains all bug security fixes from 19.11.9.52 and 19.11.10.54.
-   Fixed data race in `system.parts` table and `ALTER` query. [#6245](https://github.com/ClickHouse/ClickHouse/issues/6245) [#6513](https://github.com/ClickHouse/ClickHouse/pull/6513) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed mismatched header in streams happened in case of reading from empty distributed table with sample and prewhere. [#6167](https://github.com/ClickHouse/ClickHouse/issues/6167) ([Lixiang Qian](https://github.com/fancyqlx)) [#6823](https://github.com/ClickHouse/ClickHouse/pull/6823) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed crash when using `IN` clause with a subquery with a tuple. [#6125](https://github.com/ClickHouse/ClickHouse/issues/6125) [#6550](https://github.com/ClickHouse/ClickHouse/pull/6550) ([tavplubix](https://github.com/tavplubix))
-   Fix case with same column names in `GLOBAL JOIN ON` section. [#6181](https://github.com/ClickHouse/ClickHouse/pull/6181) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix crash when casting types to `Decimal` that do not support it. Throw exception instead. [#6297](https://github.com/ClickHouse/ClickHouse/pull/6297) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed crash in `extractAll()` function. [#6644](https://github.com/ClickHouse/ClickHouse/pull/6644) ([Artem Zuikov](https://github.com/4ertus2))
-   Query transformation for `MySQL`, `ODBC`, `JDBC` table functions now works properly for `SELECT WHERE` queries with multiple `AND` expressions. [#6381](https://github.com/ClickHouse/ClickHouse/issues/6381) [#6676](https://github.com/ClickHouse/ClickHouse/pull/6676) ([dimarub2000](https://github.com/dimarub2000))
-   Added previous declaration checks for MySQL 8 integration. [#6569](https://github.com/ClickHouse/ClickHouse/pull/6569) ([Rafael David Tinoco](https://github.com/rafaeldtinoco))

#### Security Fix {#security-fix-1}

-   Fix two vulnerabilities in codecs in decompression phase (malicious user can fabricate compressed data that will lead to buffer overflow in decompression). [#6670](https://github.com/ClickHouse/ClickHouse/pull/6670) ([Artem Zuikov](https://github.com/4ertus2))

### ClickHouse Release 19.13.3.26, 2019-08-22 {#clickhouse-release-19-13-3-26-2019-08-22}

#### Bug Fix {#bug-fix-12}

-   Fix `ALTER TABLE ... UPDATE` query for tables with `enable_mixed_granularity_parts=1`. [#6543](https://github.com/ClickHouse/ClickHouse/pull/6543) ([alesapin](https://github.com/alesapin))
-   Fix NPE when using IN clause with a subquery with a tuple. [#6125](https://github.com/ClickHouse/ClickHouse/issues/6125) [#6550](https://github.com/ClickHouse/ClickHouse/pull/6550) ([tavplubix](https://github.com/tavplubix))
-   Fixed an issue that if a stale replica becomes alive, it may still have data parts that were removed by DROP PARTITION. [#6522](https://github.com/ClickHouse/ClickHouse/issues/6522) [#6523](https://github.com/ClickHouse/ClickHouse/pull/6523) ([tavplubix](https://github.com/tavplubix))
-   Fixed issue with parsing CSV [#6426](https://github.com/ClickHouse/ClickHouse/issues/6426) [#6559](https://github.com/ClickHouse/ClickHouse/pull/6559) ([tavplubix](https://github.com/tavplubix))
-   Fixed data race in system.parts table and ALTER query. This fixes [#6245](https://github.com/ClickHouse/ClickHouse/issues/6245). [#6513](https://github.com/ClickHouse/ClickHouse/pull/6513) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed wrong code in mutations that may lead to memory corruption. Fixed segfault with read of address `0x14c0` that may happed due to concurrent `DROP TABLE` and `SELECT` from `system.parts` or `system.parts_columns`. Fixed race condition in preparation of mutation queries. Fixed deadlock caused by `OPTIMIZE` of Replicated tables and concurrent modification operations like ALTERs. [#6514](https://github.com/ClickHouse/ClickHouse/pull/6514) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed possible data loss after `ALTER DELETE` query on table with skipping index. [#6224](https://github.com/ClickHouse/ClickHouse/issues/6224) [#6282](https://github.com/ClickHouse/ClickHouse/pull/6282) ([Nikita Vasilev](https://github.com/nikvas0))

#### Security Fix {#security-fix-2}

-   If the attacker has write access to ZooKeeper and is able to run custom server available from the network where ClickHouse run, it can create custom-built malicious server that will act as ClickHouse replica and register it in ZooKeeper. When another replica will fetch data part from malicious replica, it can force clickhouse-server to write to arbitrary path on filesystem. Found by Eldar Zaitov, information security team at Yandex. [#6247](https://github.com/ClickHouse/ClickHouse/pull/6247) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.13.2.19, 2019-08-14 {#clickhouse-release-19-13-2-19-2019-08-14}

#### New Feature {#new-feature-5}

-   Sampling profiler on query level. [Example](https://gist.github.com/alexey-milovidov/92758583dd41c24c360fdb8d6a4da194). [#4247](https://github.com/ClickHouse/ClickHouse/issues/4247) ([laplab](https://github.com/laplab)) [#6124](https://github.com/ClickHouse/ClickHouse/pull/6124) ([alexey-milovidov](https://github.com/alexey-milovidov)) [#6250](https://github.com/ClickHouse/ClickHouse/pull/6250) [#6283](https://github.com/ClickHouse/ClickHouse/pull/6283) [#6386](https://github.com/ClickHouse/ClickHouse/pull/6386)
-   Allow to specify a list of columns with `COLUMNS('regexp')` expression that works like a more sophisticated variant of `*` asterisk. [#5951](https://github.com/ClickHouse/ClickHouse/pull/5951) ([mfridental](https://github.com/mfridental)), ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `CREATE TABLE AS table_function()` is now possible [#6057](https://github.com/ClickHouse/ClickHouse/pull/6057) ([dimarub2000](https://github.com/dimarub2000))
-   Adam optimizer for stochastic gradient descent is used by default in `stochasticLinearRegression()` and `stochasticLogisticRegression()` aggregate functions, because it shows good quality without almost any tuning. [#6000](https://github.com/ClickHouse/ClickHouse/pull/6000) ([Quid37](https://github.com/Quid37))
-   Added functions for working with the сustom week number [#5212](https://github.com/ClickHouse/ClickHouse/pull/5212) ([Andy Yang](https://github.com/andyyzh))
-   `RENAME` queries now work with all storages. [#5953](https://github.com/ClickHouse/ClickHouse/pull/5953) ([Ivan](https://github.com/abyss7))
-   Now client receive logs from server with any desired level by setting `send_logs_level` regardless to the log level specified in server settings. [#5964](https://github.com/ClickHouse/ClickHouse/pull/5964) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov))

#### Backward Incompatible Change {#backward-incompatible-change-4}

-   The setting `input_format_defaults_for_omitted_fields` is enabled by default. Inserts in Distributed tables need this setting to be the same on cluster (you need to set it before rolling update). It enables calculation of complex default expressions for omitted fields in `JSONEachRow` and `CSV*` formats. It should be the expected behavior but may lead to negligible performance difference. [#6043](https://github.com/ClickHouse/ClickHouse/pull/6043) ([Artem Zuikov](https://github.com/4ertus2)), [#5625](https://github.com/ClickHouse/ClickHouse/pull/5625) ([akuzm](https://github.com/akuzm))

#### Experimental Features {#experimental-features}

-   New query processing pipeline. Use `experimental_use_processors=1` option to enable it. Use for your own trouble. [#4914](https://github.com/ClickHouse/ClickHouse/pull/4914) ([Nikolai Kochetov](https://github.com/KochetovNicolai))

#### Bug Fix {#bug-fix-13}

-   Kafka integration has been fixed in this version.
-   Fixed `DoubleDelta` encoding of `Int64` for large `DoubleDelta` values, improved `DoubleDelta` encoding for random data for `Int32`. [#5998](https://github.com/ClickHouse/ClickHouse/pull/5998) ([Vasily Nemkov](https://github.com/Enmk))
-   Fixed overestimation of `max_rows_to_read` if the setting `merge_tree_uniform_read_distribution` is set to 0. [#6019](https://github.com/ClickHouse/ClickHouse/pull/6019) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Improvement {#improvement-4}

-   Throws an exception if `config.d` file does not have the corresponding root element as the config file [#6123](https://github.com/ClickHouse/ClickHouse/pull/6123) ([dimarub2000](https://github.com/dimarub2000))

#### Performance Improvement {#performance-improvement-3}

-   Optimize `count()`. Now it uses the smallest column (if possible). [#6028](https://github.com/ClickHouse/ClickHouse/pull/6028) ([Amos Bird](https://github.com/amosbird))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-5}

-   Report memory usage in performance tests. [#5899](https://github.com/ClickHouse/ClickHouse/pull/5899) ([akuzm](https://github.com/akuzm))
-   Fix build with external `libcxx` [#6010](https://github.com/ClickHouse/ClickHouse/pull/6010) ([Ivan](https://github.com/abyss7))
-   Fix shared build with `rdkafka` library [#6101](https://github.com/ClickHouse/ClickHouse/pull/6101) ([Ivan](https://github.com/abyss7))

## ClickHouse Release 19.11 {#clickhouse-release-19-11}

### ClickHouse Release 19.11.13.74, 2019-11-01 {#clickhouse-release-19-11-13-74-2019-11-01}

#### Bug Fix {#bug-fix-14}

-   Fixed rare crash in `ALTER MODIFY COLUMN` and vertical merge when one of merged/altered parts is empty (0 rows). [#6780](https://github.com/ClickHouse/ClickHouse/pull/6780) ([alesapin](https://github.com/alesapin))
-   Manual update of `SIMDJSON`. This fixes possible flooding of stderr files with bogus json diagnostic messages. [#7548](https://github.com/ClickHouse/ClickHouse/pull/7548) ([Alexander Kazakov](https://github.com/Akazz))
-   Fixed bug with `mrk` file extension for mutations ([alesapin](https://github.com/alesapin))

### ClickHouse Release 19.11.12.69, 2019-10-02 {#clickhouse-release-19-11-12-69-2019-10-02}

#### Bug Fix {#bug-fix-15}

-   Fixed performance degradation of index analysis on complex keys on large tables. This fixes [#6924](https://github.com/ClickHouse/ClickHouse/issues/6924). [#7075](https://github.com/ClickHouse/ClickHouse/pull/7075) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Avoid rare SIGSEGV while sending data in tables with Distributed engine (`Failed to send batch: file with index XXXXX is absent`). [#7032](https://github.com/ClickHouse/ClickHouse/pull/7032) ([Azat Khuzhin](https://github.com/azat))
-   Fix `Unknown identifier` with multiple joins. This fixes [#5254](https://github.com/ClickHouse/ClickHouse/issues/5254). [#7022](https://github.com/ClickHouse/ClickHouse/pull/7022) ([Artem Zuikov](https://github.com/4ertus2))

### ClickHouse Release 19.11.11.57, 2019-09-13 {#clickhouse-release-19-11-11-57-2019-09-13}

-   Fix logical error causing segfaults when selecting from Kafka empty topic. [#6902](https://github.com/ClickHouse/ClickHouse/issues/6902) [#6909](https://github.com/ClickHouse/ClickHouse/pull/6909) ([Ivan](https://github.com/abyss7))
-   Fix for function `АrrayEnumerateUniqRanked` with empty arrays in params. [#6928](https://github.com/ClickHouse/ClickHouse/pull/6928) ([proller](https://github.com/proller))

### ClickHouse Release 19.11.10.54, 2019-09-10 {#clickhouse-release-19-11-10-54-2019-09-10}

#### Bug Fix {#bug-fix-16}

-   Do store offsets for Kafka messages manually to be able to commit them all at once for all partitions. Fixes potential duplication in “one consumer - many partitions” scenario. [#6872](https://github.com/ClickHouse/ClickHouse/pull/6872) ([Ivan](https://github.com/abyss7))

### ClickHouse Release 19.11.9.52, 2019-09-6 {#clickhouse-release-19-11-9-52-2019-09-6}

-   Improve error handling in cache dictionaries. [#6737](https://github.com/ClickHouse/ClickHouse/pull/6737) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fixed bug in function `arrayEnumerateUniqRanked`. [#6779](https://github.com/ClickHouse/ClickHouse/pull/6779) ([proller](https://github.com/proller))
-   Fix `JSONExtract` function while extracting a `Tuple` from JSON. [#6718](https://github.com/ClickHouse/ClickHouse/pull/6718) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fixed possible data loss after `ALTER DELETE` query on table with skipping index. [#6224](https://github.com/ClickHouse/ClickHouse/issues/6224) [#6282](https://github.com/ClickHouse/ClickHouse/pull/6282) ([Nikita Vasilev](https://github.com/nikvas0))
-   Fixed performance test. [#6392](https://github.com/ClickHouse/ClickHouse/pull/6392) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Parquet: Fix reading boolean columns. [#6579](https://github.com/ClickHouse/ClickHouse/pull/6579) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed wrong behaviour of `nullIf` function for constant arguments. [#6518](https://github.com/ClickHouse/ClickHouse/pull/6518) ([Guillaume Tassery](https://github.com/YiuRULE)) [#6580](https://github.com/ClickHouse/ClickHouse/pull/6580) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix Kafka messages duplication problem on normal server restart. [#6597](https://github.com/ClickHouse/ClickHouse/pull/6597) ([Ivan](https://github.com/abyss7))
-   Fixed an issue when long `ALTER UPDATE` or `ALTER DELETE` may prevent regular merges to run. Prevent mutations from executing if there is no enough free threads available. [#6502](https://github.com/ClickHouse/ClickHouse/issues/6502) [#6617](https://github.com/ClickHouse/ClickHouse/pull/6617) ([tavplubix](https://github.com/tavplubix))
-   Fixed error with processing “timezone” in server configuration file. [#6709](https://github.com/ClickHouse/ClickHouse/pull/6709) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix kafka tests. [#6805](https://github.com/ClickHouse/ClickHouse/pull/6805) ([Ivan](https://github.com/abyss7))

#### Security Fix {#security-fix-3}

-   If the attacker has write access to ZooKeeper and is able to run custom server available from the network where ClickHouse runs, it can create custom-built malicious server that will act as ClickHouse replica and register it in ZooKeeper. When another replica will fetch data part from malicious replica, it can force clickhouse-server to write to arbitrary path on filesystem. Found by Eldar Zaitov, information security team at Yandex. [#6247](https://github.com/ClickHouse/ClickHouse/pull/6247) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.11.8.46, 2019-08-22 {#clickhouse-release-19-11-8-46-2019-08-22}

#### Bug Fix {#bug-fix-17}

-   Fix `ALTER TABLE ... UPDATE` query for tables with `enable_mixed_granularity_parts=1`. [#6543](https://github.com/ClickHouse/ClickHouse/pull/6543) ([alesapin](https://github.com/alesapin))
-   Fix NPE when using IN clause with a subquery with a tuple. [#6125](https://github.com/ClickHouse/ClickHouse/issues/6125) [#6550](https://github.com/ClickHouse/ClickHouse/pull/6550) ([tavplubix](https://github.com/tavplubix))
-   Fixed an issue that if a stale replica becomes alive, it may still have data parts that were removed by DROP PARTITION. [#6522](https://github.com/ClickHouse/ClickHouse/issues/6522) [#6523](https://github.com/ClickHouse/ClickHouse/pull/6523) ([tavplubix](https://github.com/tavplubix))
-   Fixed issue with parsing CSV [#6426](https://github.com/ClickHouse/ClickHouse/issues/6426) [#6559](https://github.com/ClickHouse/ClickHouse/pull/6559) ([tavplubix](https://github.com/tavplubix))
-   Fixed data race in system.parts table and ALTER query. This fixes [#6245](https://github.com/ClickHouse/ClickHouse/issues/6245). [#6513](https://github.com/ClickHouse/ClickHouse/pull/6513) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed wrong code in mutations that may lead to memory corruption. Fixed segfault with read of address `0x14c0` that may happed due to concurrent `DROP TABLE` and `SELECT` from `system.parts` or `system.parts_columns`. Fixed race condition in preparation of mutation queries. Fixed deadlock caused by `OPTIMIZE` of Replicated tables and concurrent modification operations like ALTERs. [#6514](https://github.com/ClickHouse/ClickHouse/pull/6514) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.11.7.40, 2019-08-14 {#clickhouse-release-19-11-7-40-2019-08-14}

#### Bug Fix {#bug-fix-18}

-   Kafka integration has been fixed in this version.
-   Fix segfault when using `arrayReduce` for constant arguments. [#6326](https://github.com/ClickHouse/ClickHouse/pull/6326) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed `toFloat()` monotonicity. [#6374](https://github.com/ClickHouse/ClickHouse/pull/6374) ([dimarub2000](https://github.com/dimarub2000))
-   Fix segfault with enabled `optimize_skip_unused_shards` and missing sharding key. [#6384](https://github.com/ClickHouse/ClickHouse/pull/6384) ([CurtizJ](https://github.com/CurtizJ))
-   Fixed logic of `arrayEnumerateUniqRanked` function. [#6423](https://github.com/ClickHouse/ClickHouse/pull/6423) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Removed extra verbose logging from MySQL handler. [#6389](https://github.com/ClickHouse/ClickHouse/pull/6389) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix wrong behavior and possible segfaults in `topK` and `topKWeighted` aggregated functions. [#6404](https://github.com/ClickHouse/ClickHouse/pull/6404) ([CurtizJ](https://github.com/CurtizJ))
-   Do not expose virtual columns in `system.columns` table. This is required for backward compatibility. [#6406](https://github.com/ClickHouse/ClickHouse/pull/6406) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix bug with memory allocation for string fields in complex key cache dictionary. [#6447](https://github.com/ClickHouse/ClickHouse/pull/6447) ([alesapin](https://github.com/alesapin))
-   Fix bug with enabling adaptive granularity when creating new replica for `Replicated*MergeTree` table. [#6452](https://github.com/ClickHouse/ClickHouse/pull/6452) ([alesapin](https://github.com/alesapin))
-   Fix infinite loop when reading Kafka messages. [#6354](https://github.com/ClickHouse/ClickHouse/pull/6354) ([abyss7](https://github.com/abyss7))
-   Fixed the possibility of a fabricated query to cause server crash due to stack overflow in SQL parser and possibility of stack overflow in `Merge` and `Distributed` tables [#6433](https://github.com/ClickHouse/ClickHouse/pull/6433) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed Gorilla encoding error on small sequences. [#6444](https://github.com/ClickHouse/ClickHouse/pull/6444) ([Enmk](https://github.com/Enmk))

#### Improvement {#improvement-5}

-   Allow user to override `poll_interval` and `idle_connection_timeout` settings on connection. [#6230](https://github.com/ClickHouse/ClickHouse/pull/6230) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.11.5.28, 2019-08-05 {#clickhouse-release-19-11-5-28-2019-08-05}

#### Bug Fix {#bug-fix-19}

-   Fixed the possibility of hanging queries when server is overloaded. [#6301](https://github.com/ClickHouse/ClickHouse/pull/6301) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix FPE in yandexConsistentHash function. This fixes [#6304](https://github.com/ClickHouse/ClickHouse/issues/6304). [#6126](https://github.com/ClickHouse/ClickHouse/pull/6126) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed bug in conversion of `LowCardinality` types in `AggregateFunctionFactory`. This fixes [#6257](https://github.com/ClickHouse/ClickHouse/issues/6257). [#6281](https://github.com/ClickHouse/ClickHouse/pull/6281) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix parsing of `bool` settings from `true` and `false` strings in configuration files. [#6278](https://github.com/ClickHouse/ClickHouse/pull/6278) ([alesapin](https://github.com/alesapin))
-   Fix rare bug with incompatible stream headers in queries to `Distributed` table over `MergeTree` table when part of `WHERE` moves to `PREWHERE`. [#6236](https://github.com/ClickHouse/ClickHouse/pull/6236) ([alesapin](https://github.com/alesapin))
-   Fixed overflow in integer division of signed type to unsigned type. This fixes [#6214](https://github.com/ClickHouse/ClickHouse/issues/6214). [#6233](https://github.com/ClickHouse/ClickHouse/pull/6233) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Backward Incompatible Change {#backward-incompatible-change-5}

-   `Kafka` still broken.

### ClickHouse Release 19.11.4.24, 2019-08-01 {#clickhouse-release-19-11-4-24-2019-08-01}

#### Bug Fix {#bug-fix-20}

-   Fix bug with writing secondary indices marks with adaptive granularity. [#6126](https://github.com/ClickHouse/ClickHouse/pull/6126) ([alesapin](https://github.com/alesapin))
-   Fix `WITH ROLLUP` and `WITH CUBE` modifiers of `GROUP BY` with two-level aggregation. [#6225](https://github.com/ClickHouse/ClickHouse/pull/6225) ([Anton Popov](https://github.com/CurtizJ))
-   Fixed hang in `JSONExtractRaw` function. Fixed [#6195](https://github.com/ClickHouse/ClickHouse/issues/6195) [#6198](https://github.com/ClickHouse/ClickHouse/pull/6198) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix segfault in ExternalLoader::reloadOutdated(). [#6082](https://github.com/ClickHouse/ClickHouse/pull/6082) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fixed the case when server may close listening sockets but not shutdown and continue serving remaining queries. You may end up with two running clickhouse-server processes. Sometimes, the server may return an error `bad_function_call` for remaining queries. [#6231](https://github.com/ClickHouse/ClickHouse/pull/6231) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed useless and incorrect condition on update field for initial loading of external dictionaries via ODBC, MySQL, ClickHouse and HTTP. This fixes [#6069](https://github.com/ClickHouse/ClickHouse/issues/6069) [#6083](https://github.com/ClickHouse/ClickHouse/pull/6083) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed irrelevant exception in cast of `LowCardinality(Nullable)` to not-Nullable column in case if it does not contain Nulls (e.g. in query like `SELECT CAST(CAST('Hello' AS LowCardinality(Nullable(String))) AS String)`. [#6094](https://github.com/ClickHouse/ClickHouse/issues/6094) [#6119](https://github.com/ClickHouse/ClickHouse/pull/6119) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix non-deterministic result of “uniq” aggregate function in extreme rare cases. The bug was present in all ClickHouse versions. [#6058](https://github.com/ClickHouse/ClickHouse/pull/6058) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Segfault when we set a little bit too high CIDR on the function `IPv6CIDRToRange`. [#6068](https://github.com/ClickHouse/ClickHouse/pull/6068) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Fixed small memory leak when server throw many exceptions from many different contexts. [#6144](https://github.com/ClickHouse/ClickHouse/pull/6144) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix the situation when consumer got paused before subscription and not resumed afterwards. [#6075](https://github.com/ClickHouse/ClickHouse/pull/6075) ([Ivan](https://github.com/abyss7)) Note that Kafka is broken in this version.
-   Clearing the Kafka data buffer from the previous read operation that was completed with an error [#6026](https://github.com/ClickHouse/ClickHouse/pull/6026) ([Nikolay](https://github.com/bopohaa)) Note that Kafka is broken in this version.
-   Since `StorageMergeTree::background_task_handle` is initialized in `startup()` the `MergeTreeBlockOutputStream::write()` may try to use it before initialization. Just check if it is initialized. [#6080](https://github.com/ClickHouse/ClickHouse/pull/6080) ([Ivan](https://github.com/abyss7))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-6}

-   Added official `rpm` packages. [#5740](https://github.com/ClickHouse/ClickHouse/pull/5740) ([proller](https://github.com/proller)) ([alesapin](https://github.com/alesapin))
-   Add an ability to build `.rpm` and `.tgz` packages with `packager` script. [#5769](https://github.com/ClickHouse/ClickHouse/pull/5769) ([alesapin](https://github.com/alesapin))
-   Fixes for “Arcadia” build system. [#6223](https://github.com/ClickHouse/ClickHouse/pull/6223) ([proller](https://github.com/proller))

#### Backward Incompatible Change {#backward-incompatible-change-6}

-   `Kafka` is broken in this version.

### ClickHouse Release 19.11.3.11, 2019-07-18 {#clickhouse-release-19-11-3-11-2019-07-18}

#### New Feature {#new-feature-6}

-   Added support for prepared statements. [#5331](https://github.com/ClickHouse/ClickHouse/pull/5331/) ([Alexander](https://github.com/sanych73)) [#5630](https://github.com/ClickHouse/ClickHouse/pull/5630) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `DoubleDelta` and `Gorilla` column codecs [#5600](https://github.com/ClickHouse/ClickHouse/pull/5600) ([Vasily Nemkov](https://github.com/Enmk))
-   Added `os_thread_priority` setting that allows to control the “nice” value of query processing threads that is used by OS to adjust dynamic scheduling priority. It requires `CAP_SYS_NICE` capabilities to work. This implements [#5858](https://github.com/ClickHouse/ClickHouse/issues/5858) [#5909](https://github.com/ClickHouse/ClickHouse/pull/5909) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Implement `_topic`, `_offset`, `_key` columns for Kafka engine [#5382](https://github.com/ClickHouse/ClickHouse/pull/5382) ([Ivan](https://github.com/abyss7)) Note that Kafka is broken in this version.
-   Add aggregate function combinator `-Resample` [#5590](https://github.com/ClickHouse/ClickHouse/pull/5590) ([hcz](https://github.com/hczhcz))
-   Aggregate functions `groupArrayMovingSum(win_size)(x)` and `groupArrayMovingAvg(win_size)(x)`, which calculate moving sum/avg with or without window-size limitation. [#5595](https://github.com/ClickHouse/ClickHouse/pull/5595) ([inv2004](https://github.com/inv2004))
-   Add synonim `arrayFlatten` \<-\> `flatten` [#5764](https://github.com/ClickHouse/ClickHouse/pull/5764) ([hcz](https://github.com/hczhcz))
-   Intergate H3 function `geoToH3` from Uber. [#4724](https://github.com/ClickHouse/ClickHouse/pull/4724) ([Remen Ivan](https://github.com/BHYCHIK)) [#5805](https://github.com/ClickHouse/ClickHouse/pull/5805) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Bug Fix {#bug-fix-21}

-   Implement DNS cache with asynchronous update. Separate thread resolves all hosts and updates DNS cache with period (setting `dns_cache_update_period`). It should help, when ip of hosts changes frequently. [#5857](https://github.com/ClickHouse/ClickHouse/pull/5857) ([Anton Popov](https://github.com/CurtizJ))
-   Fix segfault in `Delta` codec which affects columns with values less than 32 bits size. The bug led to random memory corruption. [#5786](https://github.com/ClickHouse/ClickHouse/pull/5786) ([alesapin](https://github.com/alesapin))
-   Fix segfault in TTL merge with non-physical columns in block. [#5819](https://github.com/ClickHouse/ClickHouse/pull/5819) ([Anton Popov](https://github.com/CurtizJ))
-   Fix rare bug in checking of part with `LowCardinality` column. Previously `checkDataPart` always fails for part with `LowCardinality` column. [#5832](https://github.com/ClickHouse/ClickHouse/pull/5832) ([alesapin](https://github.com/alesapin))
-   Avoid hanging connections when server thread pool is full. It is important for connections from `remote` table function or connections to a shard without replicas when there is long connection timeout. This fixes [#5878](https://github.com/ClickHouse/ClickHouse/issues/5878) [#5881](https://github.com/ClickHouse/ClickHouse/pull/5881) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Support for constant arguments to `evalMLModel` function. This fixes [#5817](https://github.com/ClickHouse/ClickHouse/issues/5817) [#5820](https://github.com/ClickHouse/ClickHouse/pull/5820) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed the issue when ClickHouse determines default time zone as `UCT` instead of `UTC`. This fixes [#5804](https://github.com/ClickHouse/ClickHouse/issues/5804). [#5828](https://github.com/ClickHouse/ClickHouse/pull/5828) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed buffer underflow in `visitParamExtractRaw`. This fixes [#5901](https://github.com/ClickHouse/ClickHouse/issues/5901) [#5902](https://github.com/ClickHouse/ClickHouse/pull/5902) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Now distributed `DROP/ALTER/TRUNCATE/OPTIMIZE ON CLUSTER` queries will be executed directly on leader replica. [#5757](https://github.com/ClickHouse/ClickHouse/pull/5757) ([alesapin](https://github.com/alesapin))
-   Fix `coalesce` for `ColumnConst` with `ColumnNullable` + related changes. [#5755](https://github.com/ClickHouse/ClickHouse/pull/5755) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix the `ReadBufferFromKafkaConsumer` so that it keeps reading new messages after `commit()` even if it was stalled before [#5852](https://github.com/ClickHouse/ClickHouse/pull/5852) ([Ivan](https://github.com/abyss7))
-   Fix `FULL` and `RIGHT` JOIN results when joining on `Nullable` keys in right table. [#5859](https://github.com/ClickHouse/ClickHouse/pull/5859) ([Artem Zuikov](https://github.com/4ertus2))
-   Possible fix of infinite sleeping of low-priority queries. [#5842](https://github.com/ClickHouse/ClickHouse/pull/5842) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix race condition, which cause that some queries may not appear in query_log after `SYSTEM FLUSH LOGS` query. [#5456](https://github.com/ClickHouse/ClickHouse/issues/5456) [#5685](https://github.com/ClickHouse/ClickHouse/pull/5685) ([Anton Popov](https://github.com/CurtizJ))
-   Fixed `heap-use-after-free` ASan warning in ClusterCopier caused by watch which try to use already removed copier object. [#5871](https://github.com/ClickHouse/ClickHouse/pull/5871) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed wrong `StringRef` pointer returned by some implementations of `IColumn::deserializeAndInsertFromArena`. This bug affected only unit-tests. [#5973](https://github.com/ClickHouse/ClickHouse/pull/5973) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Prevent source and intermediate array join columns of masking same name columns. [#5941](https://github.com/ClickHouse/ClickHouse/pull/5941) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix insert and select query to MySQL engine with MySQL style identifier quoting. [#5704](https://github.com/ClickHouse/ClickHouse/pull/5704) ([Winter Zhang](https://github.com/zhang2014))
-   Now `CHECK TABLE` query can work with MergeTree engine family. It returns check status and message if any for each part (or file in case of simplier engines). Also, fix bug in fetch of a broken part. [#5865](https://github.com/ClickHouse/ClickHouse/pull/5865) ([alesapin](https://github.com/alesapin))
-   Fix SPLIT_SHARED_LIBRARIES runtime [#5793](https://github.com/ClickHouse/ClickHouse/pull/5793) ([Danila Kutenin](https://github.com/danlark1))
-   Fixed time zone initialization when `/etc/localtime` is a relative symlink like `../usr/share/zoneinfo/Europe/Moscow` [#5922](https://github.com/ClickHouse/ClickHouse/pull/5922) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   clickhouse-copier: Fix use-after free on shutdown [#5752](https://github.com/ClickHouse/ClickHouse/pull/5752) ([proller](https://github.com/proller))
-   Updated `simdjson`. Fixed the issue that some invalid JSONs with zero bytes successfully parse. [#5938](https://github.com/ClickHouse/ClickHouse/pull/5938) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix shutdown of SystemLogs [#5802](https://github.com/ClickHouse/ClickHouse/pull/5802) ([Anton Popov](https://github.com/CurtizJ))
-   Fix hanging when condition in invalidate_query depends on a dictionary. [#6011](https://github.com/ClickHouse/ClickHouse/pull/6011) ([Vitaly Baranov](https://github.com/vitlibar))

#### Improvement {#improvement-6}

-   Allow unresolvable addresses in cluster configuration. They will be considered unavailable and tried to resolve at every connection attempt. This is especially useful for Kubernetes. This fixes [#5714](https://github.com/ClickHouse/ClickHouse/issues/5714) [#5924](https://github.com/ClickHouse/ClickHouse/pull/5924) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Close idle TCP connections (with one hour timeout by default). This is especially important for large clusters with multiple distributed tables on every server, because every server can possibly keep a connection pool to every other server, and after peak query concurrency, connections will stall. This fixes [#5879](https://github.com/ClickHouse/ClickHouse/issues/5879) [#5880](https://github.com/ClickHouse/ClickHouse/pull/5880) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Better quality of `topK` function. Changed the SavingSpace set behavior to remove the last element if the new element have a bigger weight. [#5833](https://github.com/ClickHouse/ClickHouse/issues/5833) [#5850](https://github.com/ClickHouse/ClickHouse/pull/5850) ([Guillaume Tassery](https://github.com/YiuRULE))
-   URL functions to work with domains now can work for incomplete URLs without scheme [#5725](https://github.com/ClickHouse/ClickHouse/pull/5725) ([alesapin](https://github.com/alesapin))
-   Checksums added to the `system.parts_columns` table. [#5874](https://github.com/ClickHouse/ClickHouse/pull/5874) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov))
-   Added `Enum` data type as a synonim for `Enum8` or `Enum16`. [#5886](https://github.com/ClickHouse/ClickHouse/pull/5886) ([dimarub2000](https://github.com/dimarub2000))
-   Full bit transpose variant for `T64` codec. Could lead to better compression with `zstd`. [#5742](https://github.com/ClickHouse/ClickHouse/pull/5742) ([Artem Zuikov](https://github.com/4ertus2))
-   Condition on `startsWith` function now can uses primary key. This fixes [#5310](https://github.com/ClickHouse/ClickHouse/issues/5310) and [#5882](https://github.com/ClickHouse/ClickHouse/issues/5882) [#5919](https://github.com/ClickHouse/ClickHouse/pull/5919) ([dimarub2000](https://github.com/dimarub2000))
-   Allow to use `clickhouse-copier` with cross-replication cluster topology by permitting empty database name. [#5745](https://github.com/ClickHouse/ClickHouse/pull/5745) ([nvartolomei](https://github.com/nvartolomei))
-   Use `UTC` as default timezone on a system without `tzdata` (e.g. bare Docker container). Before this patch, error message `Could not determine local time zone` was printed and server or client refused to start. [#5827](https://github.com/ClickHouse/ClickHouse/pull/5827) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Returned back support for floating point argument in function `quantileTiming` for backward compatibility. [#5911](https://github.com/ClickHouse/ClickHouse/pull/5911) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Show which table is missing column in error messages. [#5768](https://github.com/ClickHouse/ClickHouse/pull/5768) ([Ivan](https://github.com/abyss7))
-   Disallow run query with same query_id by various users [#5430](https://github.com/ClickHouse/ClickHouse/pull/5430) ([proller](https://github.com/proller))
-   More robust code for sending metrics to Graphite. It will work even during long multiple `RENAME TABLE` operation. [#5875](https://github.com/ClickHouse/ClickHouse/pull/5875) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   More informative error messages will be displayed when ThreadPool cannot schedule a task for execution. This fixes [#5305](https://github.com/ClickHouse/ClickHouse/issues/5305) [#5801](https://github.com/ClickHouse/ClickHouse/pull/5801) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Inverting ngramSearch to be more intuitive [#5807](https://github.com/ClickHouse/ClickHouse/pull/5807) ([Danila Kutenin](https://github.com/danlark1))
-   Add user parsing in HDFS engine builder [#5946](https://github.com/ClickHouse/ClickHouse/pull/5946) ([akonyaev90](https://github.com/akonyaev90))
-   Update default value of `max_ast_elements parameter` [#5933](https://github.com/ClickHouse/ClickHouse/pull/5933) ([Artem Konovalov](https://github.com/izebit))
-   Added a notion of obsolete settings. The obsolete setting `allow_experimental_low_cardinality_type` can be used with no effect. [0f15c01c6802f7ce1a1494c12c846be8c98944cd](https://github.com/ClickHouse/ClickHouse/commit/0f15c01c6802f7ce1a1494c12c846be8c98944cd) [Alexey Milovidov](https://github.com/alexey-milovidov)

#### Performance Improvement {#performance-improvement-4}

-   Increase number of streams to SELECT from Merge table for more uniform distribution of threads. Added setting `max_streams_multiplier_for_merge_tables`. This fixes [#5797](https://github.com/ClickHouse/ClickHouse/issues/5797) [#5915](https://github.com/ClickHouse/ClickHouse/pull/5915) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-7}

-   Add a backward compatibility test for client-server interaction with different versions of clickhouse. [#5868](https://github.com/ClickHouse/ClickHouse/pull/5868) ([alesapin](https://github.com/alesapin))
-   Test coverage information in every commit and pull request. [#5896](https://github.com/ClickHouse/ClickHouse/pull/5896) ([alesapin](https://github.com/alesapin))
-   Cooperate with address sanitizer to support our custom allocators (`Arena` and `ArenaWithFreeLists`) for better debugging of “use-after-free” errors. [#5728](https://github.com/ClickHouse/ClickHouse/pull/5728) ([akuzm](https://github.com/akuzm))
-   Switch to [LLVM libunwind implementation](https://github.com/llvm-mirror/libunwind) for C++ exception handling and for stack traces printing [#4828](https://github.com/ClickHouse/ClickHouse/pull/4828) ([Nikita Lapkov](https://github.com/laplab))
-   Add two more warnings from -Weverything [#5923](https://github.com/ClickHouse/ClickHouse/pull/5923) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Allow to build ClickHouse with Memory Sanitizer. [#3949](https://github.com/ClickHouse/ClickHouse/pull/3949) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed ubsan report about `bitTest` function in fuzz test. [#5943](https://github.com/ClickHouse/ClickHouse/pull/5943) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Docker: added possibility to init a ClickHouse instance which requires authentication. [#5727](https://github.com/ClickHouse/ClickHouse/pull/5727) ([Korviakov Andrey](https://github.com/shurshun))
-   Update librdkafka to version 1.1.0 [#5872](https://github.com/ClickHouse/ClickHouse/pull/5872) ([Ivan](https://github.com/abyss7))
-   Add global timeout for integration tests and disable some of them in tests code. [#5741](https://github.com/ClickHouse/ClickHouse/pull/5741) ([alesapin](https://github.com/alesapin))
-   Fix some ThreadSanitizer failures. [#5854](https://github.com/ClickHouse/ClickHouse/pull/5854) ([akuzm](https://github.com/akuzm))
-   The `--no-undefined` option forces the linker to check all external names for existence while linking. It’s very useful to track real dependencies between libraries in the split build mode. [#5855](https://github.com/ClickHouse/ClickHouse/pull/5855) ([Ivan](https://github.com/abyss7))
-   Added performance test for [#5797](https://github.com/ClickHouse/ClickHouse/issues/5797) [#5914](https://github.com/ClickHouse/ClickHouse/pull/5914) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed compatibility with gcc-7. [#5840](https://github.com/ClickHouse/ClickHouse/pull/5840) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added support for gcc-9. This fixes [#5717](https://github.com/ClickHouse/ClickHouse/issues/5717) [#5774](https://github.com/ClickHouse/ClickHouse/pull/5774) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed error when libunwind can be linked incorrectly. [#5948](https://github.com/ClickHouse/ClickHouse/pull/5948) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed a few warnings found by PVS-Studio. [#5921](https://github.com/ClickHouse/ClickHouse/pull/5921) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added initial support for `clang-tidy` static analyzer. [#5806](https://github.com/ClickHouse/ClickHouse/pull/5806) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Convert BSD/Linux endian macros( ‘be64toh’ and ‘htobe64’) to the Mac OS X equivalents [#5785](https://github.com/ClickHouse/ClickHouse/pull/5785) ([Fu Chen](https://github.com/fredchenbj))
-   Improved integration tests guide. [#5796](https://github.com/ClickHouse/ClickHouse/pull/5796) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Fixing build at macosx + gcc9 [#5822](https://github.com/ClickHouse/ClickHouse/pull/5822) ([filimonov](https://github.com/filimonov))
-   Fix a hard-to-spot typo: aggreAGte -\> aggregate. [#5753](https://github.com/ClickHouse/ClickHouse/pull/5753) ([akuzm](https://github.com/akuzm))
-   Fix freebsd build [#5760](https://github.com/ClickHouse/ClickHouse/pull/5760) ([proller](https://github.com/proller))
-   Add link to experimental YouTube channel to website [#5845](https://github.com/ClickHouse/ClickHouse/pull/5845) ([Ivan Blinkov](https://github.com/blinkov))
-   CMake: add option for coverage flags: WITH_COVERAGE [#5776](https://github.com/ClickHouse/ClickHouse/pull/5776) ([proller](https://github.com/proller))
-   Fix initial size of some inline PODArray’s. [#5787](https://github.com/ClickHouse/ClickHouse/pull/5787) ([akuzm](https://github.com/akuzm))
-   clickhouse-server.postinst: fix os detection for centos 6 [#5788](https://github.com/ClickHouse/ClickHouse/pull/5788) ([proller](https://github.com/proller))
-   Added Arch linux package generation. [#5719](https://github.com/ClickHouse/ClickHouse/pull/5719) ([Vladimir Chebotarev](https://github.com/excitoon))
-   Split Common/config.h by libs (dbms) [#5715](https://github.com/ClickHouse/ClickHouse/pull/5715) ([proller](https://github.com/proller))
-   Fixes for “Arcadia” build platform [#5795](https://github.com/ClickHouse/ClickHouse/pull/5795) ([proller](https://github.com/proller))
-   Fixes for unconventional build (gcc9, no submodules) [#5792](https://github.com/ClickHouse/ClickHouse/pull/5792) ([proller](https://github.com/proller))
-   Require explicit type in unalignedStore because it was proven to be bug-prone [#5791](https://github.com/ClickHouse/ClickHouse/pull/5791) ([akuzm](https://github.com/akuzm))
-   Fixes MacOS build [#5830](https://github.com/ClickHouse/ClickHouse/pull/5830) ([filimonov](https://github.com/filimonov))
-   Performance test concerning the new JIT feature with bigger dataset, as requested here [#5263](https://github.com/ClickHouse/ClickHouse/issues/5263) [#5887](https://github.com/ClickHouse/ClickHouse/pull/5887) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Run stateful tests in stress test [12693e568722f11e19859742f56428455501fd2a](https://github.com/ClickHouse/ClickHouse/commit/12693e568722f11e19859742f56428455501fd2a) ([alesapin](https://github.com/alesapin))

#### Backward Incompatible Change {#backward-incompatible-change-7}

-   `Kafka` is broken in this version.
-   Enable `adaptive_index_granularity` = 10MB by default for new `MergeTree` tables. If you created new MergeTree tables on version 19.11+, downgrade to versions prior to 19.6 will be impossible. [#5628](https://github.com/ClickHouse/ClickHouse/pull/5628) ([alesapin](https://github.com/alesapin))
-   Removed obsolete undocumented embedded dictionaries that were used by Yandex.Metrica. The functions `OSIn`, `SEIn`, `OSToRoot`, `SEToRoot`, `OSHierarchy`, `SEHierarchy` are no longer available. If you are using these functions, write email to clickhouse-feedback@yandex-team.com. Note: at the last moment we decided to keep these functions for a while. [#5780](https://github.com/ClickHouse/ClickHouse/pull/5780) ([alexey-milovidov](https://github.com/alexey-milovidov))

## ClickHouse Release 19.10 {#clickhouse-release-19-10}

### ClickHouse Release 19.10.1.5, 2019-07-12 {#clickhouse-release-19-10-1-5-2019-07-12}

#### New Feature {#new-feature-7}

-   Add new column codec: `T64`. Made for (U)IntX/EnumX/Data(Time)/DecimalX columns. It should be good for columns with constant or small range values. Codec itself allows enlarge or shrink data type without re-compression. [#5557](https://github.com/ClickHouse/ClickHouse/pull/5557) ([Artem Zuikov](https://github.com/4ertus2))
-   Add database engine `MySQL` that allow to view all the tables in remote MySQL server [#5599](https://github.com/ClickHouse/ClickHouse/pull/5599) ([Winter Zhang](https://github.com/zhang2014))
-   `bitmapContains` implementation. It’s 2x faster than `bitmapHasAny` if the second bitmap contains one element. [#5535](https://github.com/ClickHouse/ClickHouse/pull/5535) ([Zhichang Yu](https://github.com/yuzhichang))
-   Support for `crc32` function (with behaviour exactly as in MySQL or PHP). Do not use it if you need a hash function. [#5661](https://github.com/ClickHouse/ClickHouse/pull/5661) ([Remen Ivan](https://github.com/BHYCHIK))
-   Implemented `SYSTEM START/STOP DISTRIBUTED SENDS` queries to control asynchronous inserts into `Distributed` tables. [#4935](https://github.com/ClickHouse/ClickHouse/pull/4935) ([Winter Zhang](https://github.com/zhang2014))

#### Bug Fix {#bug-fix-22}

-   Ignore query execution limits and max parts size for merge limits while executing mutations. [#5659](https://github.com/ClickHouse/ClickHouse/pull/5659) ([Anton Popov](https://github.com/CurtizJ))
-   Fix bug which may lead to deduplication of normal blocks (extremely rare) and insertion of duplicate blocks (more often). [#5549](https://github.com/ClickHouse/ClickHouse/pull/5549) ([alesapin](https://github.com/alesapin))
-   Fix of function `arrayEnumerateUniqRanked` for arguments with empty arrays [#5559](https://github.com/ClickHouse/ClickHouse/pull/5559) ([proller](https://github.com/proller))
-   Don’t subscribe to Kafka topics without intent to poll any messages. [#5698](https://github.com/ClickHouse/ClickHouse/pull/5698) ([Ivan](https://github.com/abyss7))
-   Make setting `join_use_nulls` get no effect for types that cannot be inside Nullable [#5700](https://github.com/ClickHouse/ClickHouse/pull/5700) ([Olga Khvostikova](https://github.com/stavrolia))
-   Fixed `Incorrect size of index granularity` errors [#5720](https://github.com/ClickHouse/ClickHouse/pull/5720) ([coraxster](https://github.com/coraxster))
-   Fix Float to Decimal convert overflow [#5607](https://github.com/ClickHouse/ClickHouse/pull/5607) ([coraxster](https://github.com/coraxster))
-   Flush buffer when `WriteBufferFromHDFS`’s destructor is called. This fixes writing into `HDFS`. [#5684](https://github.com/ClickHouse/ClickHouse/pull/5684) ([Xindong Peng](https://github.com/eejoin))

#### Improvement {#improvement-7}

-   Treat empty cells in `CSV` as default values when the setting `input_format_defaults_for_omitted_fields` is enabled. [#5625](https://github.com/ClickHouse/ClickHouse/pull/5625) ([akuzm](https://github.com/akuzm))
-   Non-blocking loading of external dictionaries. [#5567](https://github.com/ClickHouse/ClickHouse/pull/5567) ([Vitaly Baranov](https://github.com/vitlibar))
-   Network timeouts can be dynamically changed for already established connections according to the settings. [#4558](https://github.com/ClickHouse/ClickHouse/pull/4558) ([Konstantin Podshumok](https://github.com/podshumok))
-   Using “public_suffix_list” for functions `firstSignificantSubdomain`, `cutToFirstSignificantSubdomain`. It’s using a perfect hash table generated by `gperf` with a list generated from the file: https://publicsuffix.org/list/public_suffix_list.dat. (for example, now we recognize the domain `ac.uk` as non-significant). [#5030](https://github.com/ClickHouse/ClickHouse/pull/5030) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Adopted `IPv6` data type in system tables; unified client info columns in `system.processes` and `system.query_log` [#5640](https://github.com/ClickHouse/ClickHouse/pull/5640) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Using sessions for connections with MySQL compatibility protocol. #5476 [#5646](https://github.com/ClickHouse/ClickHouse/pull/5646) ([Yuriy Baranov](https://github.com/yurriy))
-   Support more `ALTER` queries `ON CLUSTER`. [#5593](https://github.com/ClickHouse/ClickHouse/pull/5593) [#5613](https://github.com/ClickHouse/ClickHouse/pull/5613) ([sundyli](https://github.com/sundy-li))
-   Support `<logger>` section in `clickhouse-local` config file. [#5540](https://github.com/ClickHouse/ClickHouse/pull/5540) ([proller](https://github.com/proller))
-   Allow run query with `remote` table function in `clickhouse-local` [#5627](https://github.com/ClickHouse/ClickHouse/pull/5627) ([proller](https://github.com/proller))

#### Performance Improvement {#performance-improvement-5}

-   Add the possibility to write the final mark at the end of MergeTree columns. It allows to avoid useless reads for keys that are out of table data range. It is enabled only if adaptive index granularity is in use. [#5624](https://github.com/ClickHouse/ClickHouse/pull/5624) ([alesapin](https://github.com/alesapin))
-   Improved performance of MergeTree tables on very slow filesystems by reducing number of `stat` syscalls. [#5648](https://github.com/ClickHouse/ClickHouse/pull/5648) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed performance degradation in reading from MergeTree tables that was introduced in version 19.6. Fixes #5631. [#5633](https://github.com/ClickHouse/ClickHouse/pull/5633) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-8}

-   Implemented `TestKeeper` as an implementation of ZooKeeper interface used for testing [#5643](https://github.com/ClickHouse/ClickHouse/pull/5643) ([alexey-milovidov](https://github.com/alexey-milovidov)) ([levushkin aleksej](https://github.com/alexey-milovidov))
-   From now on `.sql` tests can be run isolated by server, in parallel, with random database. It allows to run them faster, add new tests with custom server configurations, and be sure that different tests does not affect each other. [#5554](https://github.com/ClickHouse/ClickHouse/pull/5554) ([Ivan](https://github.com/abyss7))
-   Remove `<name>` and `<metrics>` from performance tests [#5672](https://github.com/ClickHouse/ClickHouse/pull/5672) ([Olga Khvostikova](https://github.com/stavrolia))
-   Fixed “select_format” performance test for `Pretty` formats [#5642](https://github.com/ClickHouse/ClickHouse/pull/5642) ([alexey-milovidov](https://github.com/alexey-milovidov))

## ClickHouse Release 19.9 {#clickhouse-release-19-9}

### ClickHouse Release 19.9.3.31, 2019-07-05 {#clickhouse-release-19-9-3-31-2019-07-05}

#### Bug Fix {#bug-fix-23}

-   Fix segfault in Delta codec which affects columns with values less than 32 bits size. The bug led to random memory corruption. [#5786](https://github.com/ClickHouse/ClickHouse/pull/5786) ([alesapin](https://github.com/alesapin))
-   Fix rare bug in checking of part with LowCardinality column. [#5832](https://github.com/ClickHouse/ClickHouse/pull/5832) ([alesapin](https://github.com/alesapin))
-   Fix segfault in TTL merge with non-physical columns in block. [#5819](https://github.com/ClickHouse/ClickHouse/pull/5819) ([Anton Popov](https://github.com/CurtizJ))
-   Fix potential infinite sleeping of low-priority queries. [#5842](https://github.com/ClickHouse/ClickHouse/pull/5842) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix how ClickHouse determines default time zone as UCT instead of UTC. [#5828](https://github.com/ClickHouse/ClickHouse/pull/5828) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix bug about executing distributed DROP/ALTER/TRUNCATE/OPTIMIZE ON CLUSTER queries on follower replica before leader replica. Now they will be executed directly on leader replica. [#5757](https://github.com/ClickHouse/ClickHouse/pull/5757) ([alesapin](https://github.com/alesapin))
-   Fix race condition, which cause that some queries may not appear in query_log instantly after SYSTEM FLUSH LOGS query. [#5685](https://github.com/ClickHouse/ClickHouse/pull/5685) ([Anton Popov](https://github.com/CurtizJ))
-   Added missing support for constant arguments to `evalMLModel` function. [#5820](https://github.com/ClickHouse/ClickHouse/pull/5820) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.9.2.4, 2019-06-24 {#clickhouse-release-19-9-2-4-2019-06-24}

#### New Feature {#new-feature-8}

-   Print information about frozen parts in `system.parts` table. [#5471](https://github.com/ClickHouse/ClickHouse/pull/5471) ([proller](https://github.com/proller))
-   Ask client password on clickhouse-client start on tty if not set in arguments [#5092](https://github.com/ClickHouse/ClickHouse/pull/5092) ([proller](https://github.com/proller))
-   Implement `dictGet` and `dictGetOrDefault` functions for Decimal types. [#5394](https://github.com/ClickHouse/ClickHouse/pull/5394) ([Artem Zuikov](https://github.com/4ertus2))

#### Improvement {#improvement-8}

-   Debian init: Add service stop timeout [#5522](https://github.com/ClickHouse/ClickHouse/pull/5522) ([proller](https://github.com/proller))
-   Add setting forbidden by default to create table with suspicious types for LowCardinality [#5448](https://github.com/ClickHouse/ClickHouse/pull/5448) ([Olga Khvostikova](https://github.com/stavrolia))
-   Regression functions return model weights when not used as State in function `evalMLMethod`. [#5411](https://github.com/ClickHouse/ClickHouse/pull/5411) ([Quid37](https://github.com/Quid37))
-   Rename and improve regression methods. [#5492](https://github.com/ClickHouse/ClickHouse/pull/5492) ([Quid37](https://github.com/Quid37))
-   Clearer interfaces of string searchers. [#5586](https://github.com/ClickHouse/ClickHouse/pull/5586) ([Danila Kutenin](https://github.com/danlark1))

#### Bug Fix {#bug-fix-24}

-   Fix potential data loss in Kafka [#5445](https://github.com/ClickHouse/ClickHouse/pull/5445) ([Ivan](https://github.com/abyss7))
-   Fix potential infinite loop in `PrettySpace` format when called with zero columns [#5560](https://github.com/ClickHouse/ClickHouse/pull/5560) ([Olga Khvostikova](https://github.com/stavrolia))
-   Fixed UInt32 overflow bug in linear models. Allow eval ML model for non-const model argument. [#5516](https://github.com/ClickHouse/ClickHouse/pull/5516) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   `ALTER TABLE ... DROP INDEX IF EXISTS ...` should not raise an exception if provided index does not exist [#5524](https://github.com/ClickHouse/ClickHouse/pull/5524) ([Gleb Novikov](https://github.com/NanoBjorn))
-   Fix segfault with `bitmapHasAny` in scalar subquery [#5528](https://github.com/ClickHouse/ClickHouse/pull/5528) ([Zhichang Yu](https://github.com/yuzhichang))
-   Fixed error when replication connection pool does not retry to resolve host, even when DNS cache was dropped. [#5534](https://github.com/ClickHouse/ClickHouse/pull/5534) ([alesapin](https://github.com/alesapin))
-   Fixed `ALTER ... MODIFY TTL` on ReplicatedMergeTree. [#5539](https://github.com/ClickHouse/ClickHouse/pull/5539) ([Anton Popov](https://github.com/CurtizJ))
-   Fix INSERT into Distributed table with MATERIALIZED column [#5429](https://github.com/ClickHouse/ClickHouse/pull/5429) ([Azat Khuzhin](https://github.com/azat))
-   Fix bad alloc when truncate Join storage [#5437](https://github.com/ClickHouse/ClickHouse/pull/5437) ([TCeason](https://github.com/TCeason))
-   In recent versions of package tzdata some of files are symlinks now. The current mechanism for detecting default timezone gets broken and gives wrong names for some timezones. Now at least we force the timezone name to the contents of TZ if provided. [#5443](https://github.com/ClickHouse/ClickHouse/pull/5443) ([Ivan](https://github.com/abyss7))
-   Fix some extremely rare cases with MultiVolnitsky searcher when the constant needles in sum are at least 16KB long. The algorithm missed or overwrote the previous results which can lead to the incorrect result of `multiSearchAny`. [#5588](https://github.com/ClickHouse/ClickHouse/pull/5588) ([Danila Kutenin](https://github.com/danlark1))
-   Fix the issue when settings for ExternalData requests couldn’t use ClickHouse settings. Also, for now, settings `date_time_input_format` and `low_cardinality_allow_in_native_format` cannot be used because of the ambiguity of names (in external data it can be interpreted as table format and in the query it can be a setting). [#5455](https://github.com/ClickHouse/ClickHouse/pull/5455) ([Danila Kutenin](https://github.com/danlark1))
-   Fix bug when parts were removed only from FS without dropping them from Zookeeper. [#5520](https://github.com/ClickHouse/ClickHouse/pull/5520) ([alesapin](https://github.com/alesapin))
-   Remove debug logging from MySQL protocol [#5478](https://github.com/ClickHouse/ClickHouse/pull/5478) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Skip ZNONODE during DDL query processing [#5489](https://github.com/ClickHouse/ClickHouse/pull/5489) ([Azat Khuzhin](https://github.com/azat))
-   Fix mix `UNION ALL` result column type. There were cases with inconsistent data and column types of resulting columns. [#5503](https://github.com/ClickHouse/ClickHouse/pull/5503) ([Artem Zuikov](https://github.com/4ertus2))
-   Throw an exception on wrong integers in `dictGetT` functions instead of crash. [#5446](https://github.com/ClickHouse/ClickHouse/pull/5446) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix wrong element_count and load_factor for hashed dictionary in `system.dictionaries` table. [#5440](https://github.com/ClickHouse/ClickHouse/pull/5440) ([Azat Khuzhin](https://github.com/azat))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-9}

-   Fixed build without `Brotli` HTTP compression support (`ENABLE_BROTLI=OFF` cmake variable). [#5521](https://github.com/ClickHouse/ClickHouse/pull/5521) ([Anton Yuzhaninov](https://github.com/citrin))
-   Include roaring.h as roaring/roaring.h [#5523](https://github.com/ClickHouse/ClickHouse/pull/5523) ([Orivej Desh](https://github.com/orivej))
-   Fix gcc9 warnings in hyperscan (#line directive is evil!) [#5546](https://github.com/ClickHouse/ClickHouse/pull/5546) ([Danila Kutenin](https://github.com/danlark1))
-   Fix all warnings when compiling with gcc-9. Fix some contrib issues. Fix gcc9 ICE and submit it to bugzilla. [#5498](https://github.com/ClickHouse/ClickHouse/pull/5498) ([Danila Kutenin](https://github.com/danlark1))
-   Fixed linking with lld [#5477](https://github.com/ClickHouse/ClickHouse/pull/5477) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Remove unused specializations in dictionaries [#5452](https://github.com/ClickHouse/ClickHouse/pull/5452) ([Artem Zuikov](https://github.com/4ertus2))
-   Improvement performance tests for formatting and parsing tables for different types of files [#5497](https://github.com/ClickHouse/ClickHouse/pull/5497) ([Olga Khvostikova](https://github.com/stavrolia))
-   Fixes for parallel test run [#5506](https://github.com/ClickHouse/ClickHouse/pull/5506) ([proller](https://github.com/proller))
-   Docker: use configs from clickhouse-test [#5531](https://github.com/ClickHouse/ClickHouse/pull/5531) ([proller](https://github.com/proller))
-   Fix compile for FreeBSD [#5447](https://github.com/ClickHouse/ClickHouse/pull/5447) ([proller](https://github.com/proller))
-   Upgrade boost to 1.70 [#5570](https://github.com/ClickHouse/ClickHouse/pull/5570) ([proller](https://github.com/proller))
-   Fix build clickhouse as submodule [#5574](https://github.com/ClickHouse/ClickHouse/pull/5574) ([proller](https://github.com/proller))
-   Improve JSONExtract performance tests [#5444](https://github.com/ClickHouse/ClickHouse/pull/5444) ([Vitaly Baranov](https://github.com/vitlibar))

## ClickHouse Release 19.8 {#clickhouse-release-19-8}

### ClickHouse Release 19.8.3.8, 2019-06-11 {#clickhouse-release-19-8-3-8-2019-06-11}

#### New Features {#new-features}

-   Added functions to work with JSON [#4686](https://github.com/ClickHouse/ClickHouse/pull/4686) ([hcz](https://github.com/hczhcz)) [#5124](https://github.com/ClickHouse/ClickHouse/pull/5124). ([Vitaly Baranov](https://github.com/vitlibar))
-   Add a function basename, with a similar behaviour to a basename function, which exists in a lot of languages (`os.path.basename` in python, `basename` in PHP, etc…). Work with both an UNIX-like path or a Windows path. [#5136](https://github.com/ClickHouse/ClickHouse/pull/5136) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Added `LIMIT n, m BY` or `LIMIT m OFFSET n BY` syntax to set offset of n for LIMIT BY clause. [#5138](https://github.com/ClickHouse/ClickHouse/pull/5138) ([Anton Popov](https://github.com/CurtizJ))
-   Added new data type `SimpleAggregateFunction`, which allows to have columns with light aggregation in an `AggregatingMergeTree`. This can only be used with simple functions like `any`, `anyLast`, `sum`, `min`, `max`. [#4629](https://github.com/ClickHouse/ClickHouse/pull/4629) ([Boris Granveaud](https://github.com/bgranvea))
-   Added support for non-constant arguments in function `ngramDistance` [#5198](https://github.com/ClickHouse/ClickHouse/pull/5198) ([Danila Kutenin](https://github.com/danlark1))
-   Added functions `skewPop`, `skewSamp`, `kurtPop` and `kurtSamp` to compute for sequence skewness, sample skewness, kurtosis and sample kurtosis respectively. [#5200](https://github.com/ClickHouse/ClickHouse/pull/5200) ([hcz](https://github.com/hczhcz))
-   Support rename operation for `MaterializeView` storage. [#5209](https://github.com/ClickHouse/ClickHouse/pull/5209) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Added server which allows connecting to ClickHouse using MySQL client. [#4715](https://github.com/ClickHouse/ClickHouse/pull/4715) ([Yuriy Baranov](https://github.com/yurriy))
-   Add `toDecimal*OrZero` and `toDecimal*OrNull` functions. [#5291](https://github.com/ClickHouse/ClickHouse/pull/5291) ([Artem Zuikov](https://github.com/4ertus2))
-   Support Decimal types in functions: `quantile`, `quantiles`, `median`, `quantileExactWeighted`, `quantilesExactWeighted`, medianExactWeighted. [#5304](https://github.com/ClickHouse/ClickHouse/pull/5304) ([Artem Zuikov](https://github.com/4ertus2))
-   Added `toValidUTF8` function, which replaces all invalid UTF-8 characters by replacement character <20> (U+FFFD). [#5322](https://github.com/ClickHouse/ClickHouse/pull/5322) ([Danila Kutenin](https://github.com/danlark1))
-   Added `format` function. Formatting constant pattern (simplified Python format pattern) with the strings listed in the arguments. [#5330](https://github.com/ClickHouse/ClickHouse/pull/5330) ([Danila Kutenin](https://github.com/danlark1))
-   Added `system.detached_parts` table containing information about detached parts of `MergeTree` tables. [#5353](https://github.com/ClickHouse/ClickHouse/pull/5353) ([akuzm](https://github.com/akuzm))
-   Added `ngramSearch` function to calculate the non-symmetric difference between needle and haystack. [#5418](https://github.com/ClickHouse/ClickHouse/pull/5418)[#5422](https://github.com/ClickHouse/ClickHouse/pull/5422) ([Danila Kutenin](https://github.com/danlark1))
-   Implementation of basic machine learning methods (stochastic linear regression and logistic regression) using aggregate functions interface. Has different strategies for updating model weights (simple gradient descent, momentum method, Nesterov method). Also supports mini-batches of custom size. [#4943](https://github.com/ClickHouse/ClickHouse/pull/4943) ([Quid37](https://github.com/Quid37))
-   Implementation of `geohashEncode` and `geohashDecode` functions. [#5003](https://github.com/ClickHouse/ClickHouse/pull/5003) ([Vasily Nemkov](https://github.com/Enmk))
-   Added aggregate function `timeSeriesGroupSum`, which can aggregate different time series that sample timestamp not alignment. It will use linear interpolation between two sample timestamp and then sum time-series together. Added aggregate function `timeSeriesGroupRateSum`, which calculates the rate of time-series and then sum rates together. [#4542](https://github.com/ClickHouse/ClickHouse/pull/4542) ([Yangkuan Liu](https://github.com/LiuYangkuan))
-   Added functions `IPv4CIDRtoIPv4Range` and `IPv6CIDRtoIPv6Range` to calculate the lower and higher bounds for an IP in the subnet using a CIDR. [#5095](https://github.com/ClickHouse/ClickHouse/pull/5095) ([Guillaume Tassery](https://github.com/YiuRULE))
-   Add a X-ClickHouse-Summary header when we send a query using HTTP with enabled setting `send_progress_in_http_headers`. Return the usual information of X-ClickHouse-Progress, with additional information like how many rows and bytes were inserted in the query. [#5116](https://github.com/ClickHouse/ClickHouse/pull/5116) ([Guillaume Tassery](https://github.com/YiuRULE))

#### Improvements {#improvements}

-   Added `max_parts_in_total` setting for MergeTree family of tables (default: 100 000) that prevents unsafe specification of partition key #5166. [#5171](https://github.com/ClickHouse/ClickHouse/pull/5171) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `clickhouse-obfuscator`: derive seed for individual columns by combining initial seed with column name, not column position. This is intended to transform datasets with multiple related tables, so that tables will remain JOINable after transformation. [#5178](https://github.com/ClickHouse/ClickHouse/pull/5178) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added functions `JSONExtractRaw`, `JSONExtractKeyAndValues`. Renamed functions `jsonExtract<type>` to `JSONExtract<type>`. When something goes wrong these functions return the correspondent values, not `NULL`. Modified function `JSONExtract`, now it gets the return type from its last parameter and does not inject nullables. Implemented fallback to RapidJSON in case AVX2 instructions are not available. Simdjson library updated to a new version. [#5235](https://github.com/ClickHouse/ClickHouse/pull/5235) ([Vitaly Baranov](https://github.com/vitlibar))
-   Now `if` and `multiIf` functions do not rely on the condition’s `Nullable`, but rely on the branches for sql compatibility. [#5238](https://github.com/ClickHouse/ClickHouse/pull/5238) ([Jian Wu](https://github.com/janplus))
-   `In` predicate now generates `Null` result from `Null` input like the `Equal` function. [#5152](https://github.com/ClickHouse/ClickHouse/pull/5152) ([Jian Wu](https://github.com/janplus))
-   Check the time limit every (flush_interval / poll_timeout) number of rows from Kafka. This allows to break the reading from Kafka consumer more frequently and to check the time limits for the top-level streams [#5249](https://github.com/ClickHouse/ClickHouse/pull/5249) ([Ivan](https://github.com/abyss7))
-   Link rdkafka with bundled SASL. It should allow to use SASL SCRAM authentication [#5253](https://github.com/ClickHouse/ClickHouse/pull/5253) ([Ivan](https://github.com/abyss7))
-   Batched version of RowRefList for ALL JOINS. [#5267](https://github.com/ClickHouse/ClickHouse/pull/5267) ([Artem Zuikov](https://github.com/4ertus2))
-   clickhouse-server: more informative listen error messages. [#5268](https://github.com/ClickHouse/ClickHouse/pull/5268) ([proller](https://github.com/proller))
-   Support dictionaries in clickhouse-copier for functions in `<sharding_key>` [#5270](https://github.com/ClickHouse/ClickHouse/pull/5270) ([proller](https://github.com/proller))
-   Add new setting `kafka_commit_every_batch` to regulate Kafka committing policy.
    It allows to set commit mode: after every batch of messages is handled, or after the whole block is written to the storage. It’s a trade-off between losing some messages or reading them twice in some extreme situations. [#5308](https://github.com/ClickHouse/ClickHouse/pull/5308) ([Ivan](https://github.com/abyss7))
-   Make `windowFunnel` support other Unsigned Integer Types. [#5320](https://github.com/ClickHouse/ClickHouse/pull/5320) ([sundyli](https://github.com/sundy-li))
-   Allow to shadow virtual column `_table` in Merge engine. [#5325](https://github.com/ClickHouse/ClickHouse/pull/5325) ([Ivan](https://github.com/abyss7))
-   Make `sequenceMatch` aggregate functions support other unsigned Integer types [#5339](https://github.com/ClickHouse/ClickHouse/pull/5339) ([sundyli](https://github.com/sundy-li))
-   Better error messages if checksum mismatch is most likely caused by hardware failures. [#5355](https://github.com/ClickHouse/ClickHouse/pull/5355) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Check that underlying tables support sampling for `StorageMerge` [#5366](https://github.com/ClickHouse/ClickHouse/pull/5366) ([Ivan](https://github.com/abyss7))
-   Сlose MySQL connections after their usage in external dictionaries. It is related to issue #893. [#5395](https://github.com/ClickHouse/ClickHouse/pull/5395) ([Clément Rodriguez](https://github.com/clemrodriguez))
-   Improvements of MySQL Wire Protocol. Changed name of format to MySQLWire. Using RAII for calling RSA_free. Disabling SSL if context cannot be created. [#5419](https://github.com/ClickHouse/ClickHouse/pull/5419) ([Yuriy Baranov](https://github.com/yurriy))
-   clickhouse-client: allow to run with unaccessable history file (read-only, no disk space, file is directory, …). [#5431](https://github.com/ClickHouse/ClickHouse/pull/5431) ([proller](https://github.com/proller))
-   Respect query settings in asynchronous INSERTs into Distributed tables. [#4936](https://github.com/ClickHouse/ClickHouse/pull/4936) ([TCeason](https://github.com/TCeason))
-   Renamed functions `leastSqr` to `simpleLinearRegression`, `LinearRegression` to `linearRegression`, `LogisticRegression` to `logisticRegression`. [#5391](https://github.com/ClickHouse/ClickHouse/pull/5391) ([Nikolai Kochetov](https://github.com/KochetovNicolai))

#### Performance Improvements {#performance-improvements}

-   Parallelize processing of parts of non-replicated MergeTree tables in ALTER MODIFY query. [#4639](https://github.com/ClickHouse/ClickHouse/pull/4639) ([Ivan Kush](https://github.com/IvanKush))
-   Optimizations in regular expressions extraction. [#5193](https://github.com/ClickHouse/ClickHouse/pull/5193) [#5191](https://github.com/ClickHouse/ClickHouse/pull/5191) ([Danila Kutenin](https://github.com/danlark1))
-   Do not add right join key column to join result if it’s used only in join on section. [#5260](https://github.com/ClickHouse/ClickHouse/pull/5260) ([Artem Zuikov](https://github.com/4ertus2))
-   Freeze the Kafka buffer after first empty response. It avoids multiple invokations of `ReadBuffer::next()` for empty result in some row-parsing streams. [#5283](https://github.com/ClickHouse/ClickHouse/pull/5283) ([Ivan](https://github.com/abyss7))
-   `concat` function optimization for multiple arguments. [#5357](https://github.com/ClickHouse/ClickHouse/pull/5357) ([Danila Kutenin](https://github.com/danlark1))
-   Query optimisation. Allow push down IN statement while rewriting commа/cross join into inner one. [#5396](https://github.com/ClickHouse/ClickHouse/pull/5396) ([Artem Zuikov](https://github.com/4ertus2))
-   Upgrade our LZ4 implementation with reference one to have faster decompression. [#5070](https://github.com/ClickHouse/ClickHouse/pull/5070) ([Danila Kutenin](https://github.com/danlark1))
-   Implemented MSD radix sort (based on kxsort), and partial sorting. [#5129](https://github.com/ClickHouse/ClickHouse/pull/5129) ([Evgenii Pravda](https://github.com/kvinty))

#### Bug Fixes {#bug-fixes}

-   Fix push require columns with join [#5192](https://github.com/ClickHouse/ClickHouse/pull/5192) ([Winter Zhang](https://github.com/zhang2014))
-   Fixed bug, when ClickHouse is run by systemd, the command `sudo service clickhouse-server forcerestart` was not working as expected. [#5204](https://github.com/ClickHouse/ClickHouse/pull/5204) ([proller](https://github.com/proller))
-   Fix http error codes in DataPartsExchange (interserver http server on 9009 port always returned code 200, even on errors). [#5216](https://github.com/ClickHouse/ClickHouse/pull/5216) ([proller](https://github.com/proller))
-   Fix SimpleAggregateFunction for String longer than MAX_SMALL_STRING_SIZE [#5311](https://github.com/ClickHouse/ClickHouse/pull/5311) ([Azat Khuzhin](https://github.com/azat))
-   Fix error for `Decimal` to `Nullable(Decimal)` conversion in IN. Support other Decimal to Decimal conversions (including different scales). [#5350](https://github.com/ClickHouse/ClickHouse/pull/5350) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed FPU clobbering in simdjson library that lead to wrong calculation of `uniqHLL` and `uniqCombined` aggregate function and math functions such as `log`. [#5354](https://github.com/ClickHouse/ClickHouse/pull/5354) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed handling mixed const/nonconst cases in JSON functions. [#5435](https://github.com/ClickHouse/ClickHouse/pull/5435) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix `retention` function. Now all conditions that satisfy in a row of data are added to the data state. [#5119](https://github.com/ClickHouse/ClickHouse/pull/5119) ([小路](https://github.com/nicelulu))
-   Fix result type for `quantileExact` with Decimals. [#5304](https://github.com/ClickHouse/ClickHouse/pull/5304) ([Artem Zuikov](https://github.com/4ertus2))

#### Documentation {#documentation}

-   Translate documentation for `CollapsingMergeTree` to chinese. [#5168](https://github.com/ClickHouse/ClickHouse/pull/5168) ([张风啸](https://github.com/AlexZFX))
-   Translate some documentation about table engines to chinese.
    [#5134](https://github.com/ClickHouse/ClickHouse/pull/5134)
    [#5328](https://github.com/ClickHouse/ClickHouse/pull/5328)
    ([never lee](https://github.com/neverlee))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements}

-   Fix some sanitizer reports that show probable use-after-free.[#5139](https://github.com/ClickHouse/ClickHouse/pull/5139) [#5143](https://github.com/ClickHouse/ClickHouse/pull/5143) [#5393](https://github.com/ClickHouse/ClickHouse/pull/5393) ([Ivan](https://github.com/abyss7))
-   Move performance tests out of separate directories for convenience. [#5158](https://github.com/ClickHouse/ClickHouse/pull/5158) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix incorrect performance tests. [#5255](https://github.com/ClickHouse/ClickHouse/pull/5255) ([alesapin](https://github.com/alesapin))
-   Added a tool to calculate checksums caused by bit flips to debug hardware issues. [#5334](https://github.com/ClickHouse/ClickHouse/pull/5334) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Make runner script more usable. [#5340](https://github.com/ClickHouse/ClickHouse/pull/5340)[#5360](https://github.com/ClickHouse/ClickHouse/pull/5360) ([filimonov](https://github.com/filimonov))
-   Add small instruction how to write performance tests. [#5408](https://github.com/ClickHouse/ClickHouse/pull/5408) ([alesapin](https://github.com/alesapin))
-   Add ability to make substitutions in create, fill and drop query in performance tests [#5367](https://github.com/ClickHouse/ClickHouse/pull/5367) ([Olga Khvostikova](https://github.com/stavrolia))

## ClickHouse Release 19.7 {#clickhouse-release-19-7}

### ClickHouse Release 19.7.5.29, 2019-07-05 {#clickhouse-release-19-7-5-29-2019-07-05}

#### Bug Fix {#bug-fix-25}

-   Fix performance regression in some queries with JOIN. [#5192](https://github.com/ClickHouse/ClickHouse/pull/5192) ([Winter Zhang](https://github.com/zhang2014))

### ClickHouse Release 19.7.5.27, 2019-06-09 {#clickhouse-release-19-7-5-27-2019-06-09}

#### New Features {#new-features-1}

-   Added bitmap related functions `bitmapHasAny` and `bitmapHasAll` analogous to `hasAny` and `hasAll` functions for arrays. [#5279](https://github.com/ClickHouse/ClickHouse/pull/5279) ([Sergi Vladykin](https://github.com/svladykin))

#### Bug Fixes {#bug-fixes-1}

-   Fix segfault on `minmax` INDEX with Null value. [#5246](https://github.com/ClickHouse/ClickHouse/pull/5246) ([Nikita Vasilev](https://github.com/nikvas0))
-   Mark all input columns in LIMIT BY as required output. It fixes ‘Not found column’ error in some distributed queries. [#5407](https://github.com/ClickHouse/ClickHouse/pull/5407) ([Constantin S. Pan](https://github.com/kvap))
-   Fix “Column ‘0’ already exists” error in `SELECT .. PREWHERE` on column with DEFAULT [#5397](https://github.com/ClickHouse/ClickHouse/pull/5397) ([proller](https://github.com/proller))
-   Fix `ALTER MODIFY TTL` query on `ReplicatedMergeTree`. [#5539](https://github.com/ClickHouse/ClickHouse/pull/5539/commits) ([Anton Popov](https://github.com/CurtizJ))
-   Don’t crash the server when Kafka consumers have failed to start. [#5285](https://github.com/ClickHouse/ClickHouse/pull/5285) ([Ivan](https://github.com/abyss7))
-   Fixed bitmap functions produce wrong result. [#5359](https://github.com/ClickHouse/ClickHouse/pull/5359) ([Andy Yang](https://github.com/andyyzh))
-   Fix element_count for hashed dictionary (do not include duplicates) [#5440](https://github.com/ClickHouse/ClickHouse/pull/5440) ([Azat Khuzhin](https://github.com/azat))
-   Use contents of environment variable TZ as the name for timezone. It helps to correctly detect default timezone in some cases.[#5443](https://github.com/ClickHouse/ClickHouse/pull/5443) ([Ivan](https://github.com/abyss7))
-   Do not try to convert integers in `dictGetT` functions, because it does not work correctly. Throw an exception instead. [#5446](https://github.com/ClickHouse/ClickHouse/pull/5446) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix settings in ExternalData HTTP request. [#5455](https://github.com/ClickHouse/ClickHouse/pull/5455) ([Danila
    Kutenin](https://github.com/danlark1))
-   Fix bug when parts were removed only from FS without dropping them from Zookeeper. [#5520](https://github.com/ClickHouse/ClickHouse/pull/5520) ([alesapin](https://github.com/alesapin))
-   Fix segmentation fault in `bitmapHasAny` function. [#5528](https://github.com/ClickHouse/ClickHouse/pull/5528) ([Zhichang Yu](https://github.com/yuzhichang))
-   Fixed error when replication connection pool does not retry to resolve host, even when DNS cache was dropped. [#5534](https://github.com/ClickHouse/ClickHouse/pull/5534) ([alesapin](https://github.com/alesapin))
-   Fixed `DROP INDEX IF EXISTS` query. Now `ALTER TABLE ... DROP INDEX IF EXISTS ...` query does not raise an exception if provided index does not exist. [#5524](https://github.com/ClickHouse/ClickHouse/pull/5524) ([Gleb Novikov](https://github.com/NanoBjorn))
-   Fix union all supertype column. There were cases with inconsistent data and column types of resulting columns. [#5503](https://github.com/ClickHouse/ClickHouse/pull/5503) ([Artem Zuikov](https://github.com/4ertus2))
-   Skip ZNONODE during DDL query processing. Before if another node removes the znode in task queue, the one that
    did not process it, but already get list of children, will terminate the DDLWorker thread. [#5489](https://github.com/ClickHouse/ClickHouse/pull/5489) ([Azat Khuzhin](https://github.com/azat))
-   Fix INSERT into Distributed() table with MATERIALIZED column. [#5429](https://github.com/ClickHouse/ClickHouse/pull/5429) ([Azat Khuzhin](https://github.com/azat))

### ClickHouse Release 19.7.3.9, 2019-05-30 {#clickhouse-release-19-7-3-9-2019-05-30}

#### New Features {#new-features-2}

-   Allow to limit the range of a setting that can be specified by user.
    These constraints can be set up in user settings profile.
    [#4931](https://github.com/ClickHouse/ClickHouse/pull/4931) ([Vitaly
    Baranov](https://github.com/vitlibar))
-   Add a second version of the function `groupUniqArray` with an optional
    `max_size` parameter that limits the size of the resulting array. This
    behavior is similar to `groupArray(max_size)(x)` function.
    [#5026](https://github.com/ClickHouse/ClickHouse/pull/5026) ([Guillaume
    Tassery](https://github.com/YiuRULE))
-   For TSVWithNames/CSVWithNames input file formats, column order can now be
    determined from file header. This is controlled by
    `input_format_with_names_use_header` parameter.
    [#5081](https://github.com/ClickHouse/ClickHouse/pull/5081)
    ([Alexander](https://github.com/Akazz))

#### Bug Fixes {#bug-fixes-2}

-   Crash with uncompressed_cache + JOIN during merge (#5197)
    [#5133](https://github.com/ClickHouse/ClickHouse/pull/5133) ([Danila
    Kutenin](https://github.com/danlark1))
-   Segmentation fault on a clickhouse-client query to system tables. #5066
    [#5127](https://github.com/ClickHouse/ClickHouse/pull/5127)
    ([Ivan](https://github.com/abyss7))
-   Data loss on heavy load via KafkaEngine (#4736)
    [#5080](https://github.com/ClickHouse/ClickHouse/pull/5080)
    ([Ivan](https://github.com/abyss7))
-   Fixed very rare data race condition that could happen when executing a query with UNION ALL involving at least two SELECTs from system.columns, system.tables, system.parts, system.parts_tables or tables of Merge family and performing ALTER of columns of the related tables concurrently. [#5189](https://github.com/ClickHouse/ClickHouse/pull/5189) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Performance Improvements {#performance-improvements-1}

-   Use radix sort for sorting by single numeric column in `ORDER BY` without
    `LIMIT`. [#5106](https://github.com/ClickHouse/ClickHouse/pull/5106),
    [#4439](https://github.com/ClickHouse/ClickHouse/pull/4439)
    ([Evgenii Pravda](https://github.com/kvinty),
    [alexey-milovidov](https://github.com/alexey-milovidov))

#### Documentation {#documentation-1}

-   Translate documentation for some table engines to Chinese.
    [#5107](https://github.com/ClickHouse/ClickHouse/pull/5107),
    [#5094](https://github.com/ClickHouse/ClickHouse/pull/5094),
    [#5087](https://github.com/ClickHouse/ClickHouse/pull/5087)
    ([张风啸](https://github.com/AlexZFX)),
    [#5068](https://github.com/ClickHouse/ClickHouse/pull/5068) ([never
    lee](https://github.com/neverlee))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements-1}

-   Print UTF-8 characters properly in `clickhouse-test`.
    [#5084](https://github.com/ClickHouse/ClickHouse/pull/5084)
    ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add command line parameter for clickhouse-client to always load suggestion
    data. [#5102](https://github.com/ClickHouse/ClickHouse/pull/5102)
    ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Resolve some of PVS-Studio warnings.
    [#5082](https://github.com/ClickHouse/ClickHouse/pull/5082)
    ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Update LZ4 [#5040](https://github.com/ClickHouse/ClickHouse/pull/5040) ([Danila
    Kutenin](https://github.com/danlark1))
-   Add gperf to build requirements for upcoming pull request #5030.
    [#5110](https://github.com/ClickHouse/ClickHouse/pull/5110)
    ([proller](https://github.com/proller))

## ClickHouse Release 19.6 {#clickhouse-release-19-6}

### ClickHouse Release 19.6.3.18, 2019-06-13 {#clickhouse-release-19-6-3-18-2019-06-13}

#### Bug Fixes {#bug-fixes-3}

-   Fixed IN condition pushdown for queries from table functions `mysql` and `odbc` and corresponding table engines. This fixes #3540 and #2384. [#5313](https://github.com/ClickHouse/ClickHouse/pull/5313) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix deadlock in Zookeeper. [#5297](https://github.com/ClickHouse/ClickHouse/pull/5297) ([github1youlc](https://github.com/github1youlc))
-   Allow quoted decimals in CSV. [#5284](https://github.com/ClickHouse/ClickHouse/pull/5284) ([Artem Zuikov](https://github.com/4ertus2)
-   Disallow conversion from float Inf/NaN into Decimals (throw exception). [#5282](https://github.com/ClickHouse/ClickHouse/pull/5282) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix data race in rename query. [#5247](https://github.com/ClickHouse/ClickHouse/pull/5247) ([Winter Zhang](https://github.com/zhang2014))
-   Temporarily disable LFAlloc. Usage of LFAlloc might lead to a lot of MAP_FAILED in allocating UncompressedCache and in a result to crashes of queries at high loaded servers. [cfdba93](https://github.com/ClickHouse/ClickHouse/commit/cfdba938ce22f16efeec504f7f90206a515b1280)([Danila Kutenin](https://github.com/danlark1))

### ClickHouse Release 19.6.2.11, 2019-05-13 {#clickhouse-release-19-6-2-11-2019-05-13}

#### New Features {#new-features-3}

-   TTL expressions for columns and tables. [#4212](https://github.com/ClickHouse/ClickHouse/pull/4212) ([Anton Popov](https://github.com/CurtizJ))
-   Added support for `brotli` compression for HTTP responses (Accept-Encoding: br) [#4388](https://github.com/ClickHouse/ClickHouse/pull/4388) ([Mikhail](https://github.com/fandyushin))
-   Added new function `isValidUTF8` for checking whether a set of bytes is correctly utf-8 encoded. [#4934](https://github.com/ClickHouse/ClickHouse/pull/4934) ([Danila Kutenin](https://github.com/danlark1))
-   Add new load balancing policy `first_or_random` which sends queries to the first specified host and if it’s inaccessible send queries to random hosts of shard. Useful for cross-replication topology setups. [#5012](https://github.com/ClickHouse/ClickHouse/pull/5012) ([nvartolomei](https://github.com/nvartolomei))

#### Experimental Features {#experimental-features-1}

-   Add setting `index_granularity_bytes` (adaptive index granularity) for MergeTree\* tables family. [#4826](https://github.com/ClickHouse/ClickHouse/pull/4826) ([alesapin](https://github.com/alesapin))

#### Improvements {#improvements-1}

-   Added support for non-constant and negative size and length arguments for function `substringUTF8`. [#4989](https://github.com/ClickHouse/ClickHouse/pull/4989) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Disable push-down to right table in left join, left table in right join, and both tables in full join. This fixes wrong JOIN results in some cases. [#4846](https://github.com/ClickHouse/ClickHouse/pull/4846) ([Ivan](https://github.com/abyss7))
-   `clickhouse-copier`: auto upload task configuration from `--task-file` option [#4876](https://github.com/ClickHouse/ClickHouse/pull/4876) ([proller](https://github.com/proller))
-   Added typos handler for storage factory and table functions factory. [#4891](https://github.com/ClickHouse/ClickHouse/pull/4891) ([Danila Kutenin](https://github.com/danlark1))
-   Support asterisks and qualified asterisks for multiple joins without subqueries [#4898](https://github.com/ClickHouse/ClickHouse/pull/4898) ([Artem Zuikov](https://github.com/4ertus2))
-   Make missing column error message more user friendly. [#4915](https://github.com/ClickHouse/ClickHouse/pull/4915) ([Artem Zuikov](https://github.com/4ertus2))

#### Performance Improvements {#performance-improvements-2}

-   Significant speedup of ASOF JOIN [#4924](https://github.com/ClickHouse/ClickHouse/pull/4924) ([Martijn Bakker](https://github.com/Gladdy))

#### Backward Incompatible Changes {#backward-incompatible-changes}

-   HTTP header `Query-Id` was renamed to `X-ClickHouse-Query-Id` for consistency. [#4972](https://github.com/ClickHouse/ClickHouse/pull/4972) ([Mikhail](https://github.com/fandyushin))

#### Bug Fixes {#bug-fixes-4}

-   Fixed potential null pointer dereference in `clickhouse-copier`. [#4900](https://github.com/ClickHouse/ClickHouse/pull/4900) ([proller](https://github.com/proller))
-   Fixed error on query with JOIN + ARRAY JOIN [#4938](https://github.com/ClickHouse/ClickHouse/pull/4938) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed hanging on start of the server when a dictionary depends on another dictionary via a database with engine=Dictionary. [#4962](https://github.com/ClickHouse/ClickHouse/pull/4962) ([Vitaly Baranov](https://github.com/vitlibar))
-   Partially fix distributed_product_mode = local. It’s possible to allow columns of local tables in where/having/order by/… via table aliases. Throw exception if table does not have alias. There’s not possible to access to the columns without table aliases yet. [#4986](https://github.com/ClickHouse/ClickHouse/pull/4986) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix potentially wrong result for `SELECT DISTINCT` with `JOIN` [#5001](https://github.com/ClickHouse/ClickHouse/pull/5001) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed very rare data race condition that could happen when executing a query with UNION ALL involving at least two SELECTs from system.columns, system.tables, system.parts, system.parts_tables or tables of Merge family and performing ALTER of columns of the related tables concurrently. [#5189](https://github.com/ClickHouse/ClickHouse/pull/5189) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements-2}

-   Fixed test failures when running clickhouse-server on different host [#4713](https://github.com/ClickHouse/ClickHouse/pull/4713) ([Vasily Nemkov](https://github.com/Enmk))
-   clickhouse-test: Disable color control sequences in non tty environment. [#4937](https://github.com/ClickHouse/ClickHouse/pull/4937) ([alesapin](https://github.com/alesapin))
-   clickhouse-test: Allow use any test database (remove `test.` qualification where it possible) [#5008](https://github.com/ClickHouse/ClickHouse/pull/5008) ([proller](https://github.com/proller))
-   Fix ubsan errors [#5037](https://github.com/ClickHouse/ClickHouse/pull/5037) ([Vitaly Baranov](https://github.com/vitlibar))
-   Yandex LFAlloc was added to ClickHouse to allocate MarkCache and UncompressedCache data in different ways to catch segfaults more reliable [#4995](https://github.com/ClickHouse/ClickHouse/pull/4995) ([Danila Kutenin](https://github.com/danlark1))
-   Python util to help with backports and changelogs. [#4949](https://github.com/ClickHouse/ClickHouse/pull/4949) ([Ivan](https://github.com/abyss7))

## ClickHouse Release 19.5 {#clickhouse-release-19-5}

### ClickHouse Release 19.5.4.22, 2019-05-13 {#clickhouse-release-19-5-4-22-2019-05-13}

#### Bug Fixes {#bug-fixes-5}

-   Fixed possible crash in bitmap\* functions [#5220](https://github.com/ClickHouse/ClickHouse/pull/5220) [#5228](https://github.com/ClickHouse/ClickHouse/pull/5228) ([Andy Yang](https://github.com/andyyzh))
-   Fixed very rare data race condition that could happen when executing a query with UNION ALL involving at least two SELECTs from system.columns, system.tables, system.parts, system.parts_tables or tables of Merge family and performing ALTER of columns of the related tables concurrently. [#5189](https://github.com/ClickHouse/ClickHouse/pull/5189) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed error `Set for IN is not created yet in case of using single LowCardinality column in the left part of IN`. This error happened if LowCardinality column was the part of primary key. #5031 [#5154](https://github.com/ClickHouse/ClickHouse/pull/5154) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Modification of retention function: If a row satisfies both the first and NTH condition, only the first satisfied condition is added to the data state. Now all conditions that satisfy in a row of data are added to the data state. [#5119](https://github.com/ClickHouse/ClickHouse/pull/5119) ([小路](https://github.com/nicelulu))

### ClickHouse Release 19.5.3.8, 2019-04-18 {#clickhouse-release-19-5-3-8-2019-04-18}

#### Bug Fixes {#bug-fixes-6}

-   Fixed type of setting `max_partitions_per_insert_block` from boolean to UInt64. [#5028](https://github.com/ClickHouse/ClickHouse/pull/5028) ([Mohammad Hossein Sekhavat](https://github.com/mhsekhavat))

### ClickHouse Release 19.5.2.6, 2019-04-15 {#clickhouse-release-19-5-2-6-2019-04-15}

#### New Features {#new-features-4}

-   [Hyperscan](https://github.com/intel/hyperscan) multiple regular expression matching was added (functions `multiMatchAny`, `multiMatchAnyIndex`, `multiFuzzyMatchAny`, `multiFuzzyMatchAnyIndex`). [#4780](https://github.com/ClickHouse/ClickHouse/pull/4780), [#4841](https://github.com/ClickHouse/ClickHouse/pull/4841) ([Danila Kutenin](https://github.com/danlark1))
-   `multiSearchFirstPosition` function was added. [#4780](https://github.com/ClickHouse/ClickHouse/pull/4780) ([Danila Kutenin](https://github.com/danlark1))
-   Implement the predefined expression filter per row for tables. [#4792](https://github.com/ClickHouse/ClickHouse/pull/4792) ([Ivan](https://github.com/abyss7))
-   A new type of data skipping indices based on bloom filters (can be used for `equal`, `in` and `like` functions). [#4499](https://github.com/ClickHouse/ClickHouse/pull/4499) ([Nikita Vasilev](https://github.com/nikvas0))
-   Added `ASOF JOIN` which allows to run queries that join to the most recent value known. [#4774](https://github.com/ClickHouse/ClickHouse/pull/4774) [#4867](https://github.com/ClickHouse/ClickHouse/pull/4867) [#4863](https://github.com/ClickHouse/ClickHouse/pull/4863) [#4875](https://github.com/ClickHouse/ClickHouse/pull/4875) ([Martijn Bakker](https://github.com/Gladdy), [Artem Zuikov](https://github.com/4ertus2))
-   Rewrite multiple `COMMA JOIN` to `CROSS JOIN`. Then rewrite them to `INNER JOIN` if possible. [#4661](https://github.com/ClickHouse/ClickHouse/pull/4661) ([Artem Zuikov](https://github.com/4ertus2))

#### Improvement {#improvement-9}

-   `topK` and `topKWeighted` now supports custom `loadFactor` (fixes issue [#4252](https://github.com/ClickHouse/ClickHouse/issues/4252)). [#4634](https://github.com/ClickHouse/ClickHouse/pull/4634) ([Kirill Danshin](https://github.com/kirillDanshin))
-   Allow to use `parallel_replicas_count > 1` even for tables without sampling (the setting is simply ignored for them). In previous versions it was lead to exception. [#4637](https://github.com/ClickHouse/ClickHouse/pull/4637) ([Alexey Elymanov](https://github.com/digitalist))
-   Support for `CREATE OR REPLACE VIEW`. Allow to create a view or set a new definition in a single statement. [#4654](https://github.com/ClickHouse/ClickHouse/pull/4654) ([Boris Granveaud](https://github.com/bgranvea))
-   `Buffer` table engine now supports `PREWHERE`. [#4671](https://github.com/ClickHouse/ClickHouse/pull/4671) ([Yangkuan Liu](https://github.com/LiuYangkuan))
-   Add ability to start replicated table without metadata in zookeeper in `readonly` mode. [#4691](https://github.com/ClickHouse/ClickHouse/pull/4691) ([alesapin](https://github.com/alesapin))
-   Fixed flicker of progress bar in clickhouse-client. The issue was most noticeable when using `FORMAT Null` with streaming queries. [#4811](https://github.com/ClickHouse/ClickHouse/pull/4811) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Allow to disable functions with `hyperscan` library on per user basis to limit potentially excessive and uncontrolled resource usage. [#4816](https://github.com/ClickHouse/ClickHouse/pull/4816) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add version number logging in all errors. [#4824](https://github.com/ClickHouse/ClickHouse/pull/4824) ([proller](https://github.com/proller))
-   Added restriction to the `multiMatch` functions which requires string size to fit into `unsigned int`. Also added the number of arguments limit to the `multiSearch` functions. [#4834](https://github.com/ClickHouse/ClickHouse/pull/4834) ([Danila Kutenin](https://github.com/danlark1))
-   Improved usage of scratch space and error handling in Hyperscan. [#4866](https://github.com/ClickHouse/ClickHouse/pull/4866) ([Danila Kutenin](https://github.com/danlark1))
-   Fill `system.graphite_detentions` from a table config of `*GraphiteMergeTree` engine tables. [#4584](https://github.com/ClickHouse/ClickHouse/pull/4584) ([Mikhail f. Shiryaev](https://github.com/Felixoid))
-   Rename `trigramDistance` function to `ngramDistance` and add more functions with `CaseInsensitive` and `UTF`. [#4602](https://github.com/ClickHouse/ClickHouse/pull/4602) ([Danila Kutenin](https://github.com/danlark1))
-   Improved data skipping indices calculation. [#4640](https://github.com/ClickHouse/ClickHouse/pull/4640) ([Nikita Vasilev](https://github.com/nikvas0))
-   Keep ordinary, `DEFAULT`, `MATERIALIZED` and `ALIAS` columns in a single list (fixes issue [#2867](https://github.com/ClickHouse/ClickHouse/issues/2867)). [#4707](https://github.com/ClickHouse/ClickHouse/pull/4707) ([Alex Zatelepin](https://github.com/ztlpn))

#### Bug Fix {#bug-fix-26}

-   Avoid `std::terminate` in case of memory allocation failure. Now `std::bad_alloc` exception is thrown as expected. [#4665](https://github.com/ClickHouse/ClickHouse/pull/4665) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixes capnproto reading from buffer. Sometimes files wasn’t loaded successfully by HTTP. [#4674](https://github.com/ClickHouse/ClickHouse/pull/4674) ([Vladislav](https://github.com/smirnov-vs))
-   Fix error `Unknown log entry type: 0` after `OPTIMIZE TABLE FINAL` query. [#4683](https://github.com/ClickHouse/ClickHouse/pull/4683) ([Amos Bird](https://github.com/amosbird))
-   Wrong arguments to `hasAny` or `hasAll` functions may lead to segfault. [#4698](https://github.com/ClickHouse/ClickHouse/pull/4698) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Deadlock may happen while executing `DROP DATABASE dictionary` query. [#4701](https://github.com/ClickHouse/ClickHouse/pull/4701) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix undefined behavior in `median` and `quantile` functions. [#4702](https://github.com/ClickHouse/ClickHouse/pull/4702) ([hcz](https://github.com/hczhcz))
-   Fix compression level detection when `network_compression_method` in lowercase. Broken in v19.1. [#4706](https://github.com/ClickHouse/ClickHouse/pull/4706) ([proller](https://github.com/proller))
-   Fixed ignorance of `<timezone>UTC</timezone>` setting (fixes issue [#4658](https://github.com/ClickHouse/ClickHouse/issues/4658)). [#4718](https://github.com/ClickHouse/ClickHouse/pull/4718) ([proller](https://github.com/proller))
-   Fix `histogram` function behaviour with `Distributed` tables. [#4741](https://github.com/ClickHouse/ClickHouse/pull/4741) ([olegkv](https://github.com/olegkv))
-   Fixed tsan report `destroy of a locked mutex`. [#4742](https://github.com/ClickHouse/ClickHouse/pull/4742) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed TSan report on shutdown due to race condition in system logs usage. Fixed potential use-after-free on shutdown when part_log is enabled. [#4758](https://github.com/ClickHouse/ClickHouse/pull/4758) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix recheck parts in `ReplicatedMergeTreeAlterThread` in case of error. [#4772](https://github.com/ClickHouse/ClickHouse/pull/4772) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Arithmetic operations on intermediate aggregate function states were not working for constant arguments (such as subquery results). [#4776](https://github.com/ClickHouse/ClickHouse/pull/4776) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Always backquote column names in metadata. Otherwise it’s impossible to create a table with column named `index` (server won’t restart due to malformed `ATTACH` query in metadata). [#4782](https://github.com/ClickHouse/ClickHouse/pull/4782) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix crash in `ALTER ... MODIFY ORDER BY` on `Distributed` table. [#4790](https://github.com/ClickHouse/ClickHouse/pull/4790) ([TCeason](https://github.com/TCeason))
-   Fix segfault in `JOIN ON` with enabled `enable_optimize_predicate_expression`. [#4794](https://github.com/ClickHouse/ClickHouse/pull/4794) ([Winter Zhang](https://github.com/zhang2014))
-   Fix bug with adding an extraneous row after consuming a protobuf message from Kafka. [#4808](https://github.com/ClickHouse/ClickHouse/pull/4808) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix crash of `JOIN` on not-nullable vs nullable column. Fix `NULLs` in right keys in `ANY JOIN` + `join_use_nulls`. [#4815](https://github.com/ClickHouse/ClickHouse/pull/4815) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix segmentation fault in `clickhouse-copier`. [#4835](https://github.com/ClickHouse/ClickHouse/pull/4835) ([proller](https://github.com/proller))
-   Fixed race condition in `SELECT` from `system.tables` if the table is renamed or altered concurrently. [#4836](https://github.com/ClickHouse/ClickHouse/pull/4836) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed data race when fetching data part that is already obsolete. [#4839](https://github.com/ClickHouse/ClickHouse/pull/4839) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed rare data race that can happen during `RENAME` table of MergeTree family. [#4844](https://github.com/ClickHouse/ClickHouse/pull/4844) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed segmentation fault in function `arrayIntersect`. Segmentation fault could happen if function was called with mixed constant and ordinary arguments. [#4847](https://github.com/ClickHouse/ClickHouse/pull/4847) ([Lixiang Qian](https://github.com/fancyqlx))
-   Fixed reading from `Array(LowCardinality)` column in rare case when column contained a long sequence of empty arrays. [#4850](https://github.com/ClickHouse/ClickHouse/pull/4850) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix crash in `FULL/RIGHT JOIN` when we joining on nullable vs not nullable. [#4855](https://github.com/ClickHouse/ClickHouse/pull/4855) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix `No message received` exception while fetching parts between replicas. [#4856](https://github.com/ClickHouse/ClickHouse/pull/4856) ([alesapin](https://github.com/alesapin))
-   Fixed `arrayIntersect` function wrong result in case of several repeated values in single array. [#4871](https://github.com/ClickHouse/ClickHouse/pull/4871) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix a race condition during concurrent `ALTER COLUMN` queries that could lead to a server crash (fixes issue [#3421](https://github.com/ClickHouse/ClickHouse/issues/3421)). [#4592](https://github.com/ClickHouse/ClickHouse/pull/4592) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fix incorrect result in `FULL/RIGHT JOIN` with const column. [#4723](https://github.com/ClickHouse/ClickHouse/pull/4723) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix duplicates in `GLOBAL JOIN` with asterisk. [#4705](https://github.com/ClickHouse/ClickHouse/pull/4705) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix parameter deduction in `ALTER MODIFY` of column `CODEC` when column type is not specified. [#4883](https://github.com/ClickHouse/ClickHouse/pull/4883) ([alesapin](https://github.com/alesapin))
-   Functions `cutQueryStringAndFragment()` and `queryStringAndFragment()` now works correctly when `URL` contains a fragment and no query. [#4894](https://github.com/ClickHouse/ClickHouse/pull/4894) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix rare bug when setting `min_bytes_to_use_direct_io` is greater than zero, which occures when thread have to seek backward in column file. [#4897](https://github.com/ClickHouse/ClickHouse/pull/4897) ([alesapin](https://github.com/alesapin))
-   Fix wrong argument types for aggregate functions with `LowCardinality` arguments (fixes issue [#4919](https://github.com/ClickHouse/ClickHouse/issues/4919)). [#4922](https://github.com/ClickHouse/ClickHouse/pull/4922) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix wrong name qualification in `GLOBAL JOIN`. [#4969](https://github.com/ClickHouse/ClickHouse/pull/4969) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix function `toISOWeek` result for year 1970. [#4988](https://github.com/ClickHouse/ClickHouse/pull/4988) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix `DROP`, `TRUNCATE` and `OPTIMIZE` queries duplication, when executed on `ON CLUSTER` for `ReplicatedMergeTree*` tables family. [#4991](https://github.com/ClickHouse/ClickHouse/pull/4991) ([alesapin](https://github.com/alesapin))

#### Backward Incompatible Change {#backward-incompatible-change-8}

-   Rename setting `insert_sample_with_metadata` to setting `input_format_defaults_for_omitted_fields`. [#4771](https://github.com/ClickHouse/ClickHouse/pull/4771) ([Artem Zuikov](https://github.com/4ertus2))
-   Added setting `max_partitions_per_insert_block` (with value 100 by default). If inserted block contains larger number of partitions, an exception is thrown. Set it to 0 if you want to remove the limit (not recommended). [#4845](https://github.com/ClickHouse/ClickHouse/pull/4845) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Multi-search functions were renamed (`multiPosition` to `multiSearchAllPositions`, `multiSearch` to `multiSearchAny`, `firstMatch` to `multiSearchFirstIndex`). [#4780](https://github.com/ClickHouse/ClickHouse/pull/4780) ([Danila Kutenin](https://github.com/danlark1))

#### Performance Improvement {#performance-improvement-6}

-   Optimize Volnitsky searcher by inlining, giving about 5-10% search improvement for queries with many needles or many similar bigrams. [#4862](https://github.com/ClickHouse/ClickHouse/pull/4862) ([Danila Kutenin](https://github.com/danlark1))
-   Fix performance issue when setting `use_uncompressed_cache` is greater than zero, which appeared when all read data contained in cache. [#4913](https://github.com/ClickHouse/ClickHouse/pull/4913) ([alesapin](https://github.com/alesapin))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-10}

-   Hardening debug build: more granular memory mappings and ASLR; add memory protection for mark cache and index. This allows to find more memory stomping bugs in case when ASan and MSan cannot do it. [#4632](https://github.com/ClickHouse/ClickHouse/pull/4632) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add support for cmake variables `ENABLE_PROTOBUF`, `ENABLE_PARQUET` and `ENABLE_BROTLI` which allows to enable/disable the above features (same as we can do for librdkafka, mysql, etc). [#4669](https://github.com/ClickHouse/ClickHouse/pull/4669) ([Silviu Caragea](https://github.com/silviucpp))
-   Add ability to print process list and stacktraces of all threads if some queries are hung after test run. [#4675](https://github.com/ClickHouse/ClickHouse/pull/4675) ([alesapin](https://github.com/alesapin))
-   Add retries on `Connection loss` error in `clickhouse-test`. [#4682](https://github.com/ClickHouse/ClickHouse/pull/4682) ([alesapin](https://github.com/alesapin))
-   Add freebsd build with vagrant and build with thread sanitizer to packager script. [#4712](https://github.com/ClickHouse/ClickHouse/pull/4712) [#4748](https://github.com/ClickHouse/ClickHouse/pull/4748) ([alesapin](https://github.com/alesapin))
-   Now user asked for password for user `'default'` during installation. [#4725](https://github.com/ClickHouse/ClickHouse/pull/4725) ([proller](https://github.com/proller))
-   Suppress warning in `rdkafka` library. [#4740](https://github.com/ClickHouse/ClickHouse/pull/4740) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Allow ability to build without ssl. [#4750](https://github.com/ClickHouse/ClickHouse/pull/4750) ([proller](https://github.com/proller))
-   Add a way to launch clickhouse-server image from a custom user. [#4753](https://github.com/ClickHouse/ClickHouse/pull/4753) ([Mikhail f. Shiryaev](https://github.com/Felixoid))
-   Upgrade contrib boost to 1.69. [#4793](https://github.com/ClickHouse/ClickHouse/pull/4793) ([proller](https://github.com/proller))
-   Disable usage of `mremap` when compiled with Thread Sanitizer. Surprisingly enough, TSan does not intercept `mremap` (though it does intercept `mmap`, `munmap`) that leads to false positives. Fixed TSan report in stateful tests. [#4859](https://github.com/ClickHouse/ClickHouse/pull/4859) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add test checking using format schema via HTTP interface. [#4864](https://github.com/ClickHouse/ClickHouse/pull/4864) ([Vitaly Baranov](https://github.com/vitlibar))

## ClickHouse Release 19.4 {#clickhouse-release-19-4}

### ClickHouse Release 19.4.4.33, 2019-04-17 {#clickhouse-release-19-4-4-33-2019-04-17}

#### Bug Fixes {#bug-fixes-7}

-   Avoid `std::terminate` in case of memory allocation failure. Now `std::bad_alloc` exception is thrown as expected. [#4665](https://github.com/ClickHouse/ClickHouse/pull/4665) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixes capnproto reading from buffer. Sometimes files wasn’t loaded successfully by HTTP. [#4674](https://github.com/ClickHouse/ClickHouse/pull/4674) ([Vladislav](https://github.com/smirnov-vs))
-   Fix error `Unknown log entry type: 0` after `OPTIMIZE TABLE FINAL` query. [#4683](https://github.com/ClickHouse/ClickHouse/pull/4683) ([Amos Bird](https://github.com/amosbird))
-   Wrong arguments to `hasAny` or `hasAll` functions may lead to segfault. [#4698](https://github.com/ClickHouse/ClickHouse/pull/4698) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Deadlock may happen while executing `DROP DATABASE dictionary` query. [#4701](https://github.com/ClickHouse/ClickHouse/pull/4701) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix undefined behavior in `median` and `quantile` functions. [#4702](https://github.com/ClickHouse/ClickHouse/pull/4702) ([hcz](https://github.com/hczhcz))
-   Fix compression level detection when `network_compression_method` in lowercase. Broken in v19.1. [#4706](https://github.com/ClickHouse/ClickHouse/pull/4706) ([proller](https://github.com/proller))
-   Fixed ignorance of `<timezone>UTC</timezone>` setting (fixes issue [#4658](https://github.com/ClickHouse/ClickHouse/issues/4658)). [#4718](https://github.com/ClickHouse/ClickHouse/pull/4718) ([proller](https://github.com/proller))
-   Fix `histogram` function behaviour with `Distributed` tables. [#4741](https://github.com/ClickHouse/ClickHouse/pull/4741) ([olegkv](https://github.com/olegkv))
-   Fixed tsan report `destroy of a locked mutex`. [#4742](https://github.com/ClickHouse/ClickHouse/pull/4742) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed TSan report on shutdown due to race condition in system logs usage. Fixed potential use-after-free on shutdown when part_log is enabled. [#4758](https://github.com/ClickHouse/ClickHouse/pull/4758) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix recheck parts in `ReplicatedMergeTreeAlterThread` in case of error. [#4772](https://github.com/ClickHouse/ClickHouse/pull/4772) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Arithmetic operations on intermediate aggregate function states were not working for constant arguments (such as subquery results). [#4776](https://github.com/ClickHouse/ClickHouse/pull/4776) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Always backquote column names in metadata. Otherwise it’s impossible to create a table with column named `index` (server won’t restart due to malformed `ATTACH` query in metadata). [#4782](https://github.com/ClickHouse/ClickHouse/pull/4782) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix crash in `ALTER ... MODIFY ORDER BY` on `Distributed` table. [#4790](https://github.com/ClickHouse/ClickHouse/pull/4790) ([TCeason](https://github.com/TCeason))
-   Fix segfault in `JOIN ON` with enabled `enable_optimize_predicate_expression`. [#4794](https://github.com/ClickHouse/ClickHouse/pull/4794) ([Winter Zhang](https://github.com/zhang2014))
-   Fix bug with adding an extraneous row after consuming a protobuf message from Kafka. [#4808](https://github.com/ClickHouse/ClickHouse/pull/4808) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix segmentation fault in `clickhouse-copier`. [#4835](https://github.com/ClickHouse/ClickHouse/pull/4835) ([proller](https://github.com/proller))
-   Fixed race condition in `SELECT` from `system.tables` if the table is renamed or altered concurrently. [#4836](https://github.com/ClickHouse/ClickHouse/pull/4836) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed data race when fetching data part that is already obsolete. [#4839](https://github.com/ClickHouse/ClickHouse/pull/4839) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed rare data race that can happen during `RENAME` table of MergeTree family. [#4844](https://github.com/ClickHouse/ClickHouse/pull/4844) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed segmentation fault in function `arrayIntersect`. Segmentation fault could happen if function was called with mixed constant and ordinary arguments. [#4847](https://github.com/ClickHouse/ClickHouse/pull/4847) ([Lixiang Qian](https://github.com/fancyqlx))
-   Fixed reading from `Array(LowCardinality)` column in rare case when column contained a long sequence of empty arrays. [#4850](https://github.com/ClickHouse/ClickHouse/pull/4850) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix `No message received` exception while fetching parts between replicas. [#4856](https://github.com/ClickHouse/ClickHouse/pull/4856) ([alesapin](https://github.com/alesapin))
-   Fixed `arrayIntersect` function wrong result in case of several repeated values in single array. [#4871](https://github.com/ClickHouse/ClickHouse/pull/4871) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix a race condition during concurrent `ALTER COLUMN` queries that could lead to a server crash (fixes issue [#3421](https://github.com/ClickHouse/ClickHouse/issues/3421)). [#4592](https://github.com/ClickHouse/ClickHouse/pull/4592) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fix parameter deduction in `ALTER MODIFY` of column `CODEC` when column type is not specified. [#4883](https://github.com/ClickHouse/ClickHouse/pull/4883) ([alesapin](https://github.com/alesapin))
-   Functions `cutQueryStringAndFragment()` and `queryStringAndFragment()` now works correctly when `URL` contains a fragment and no query. [#4894](https://github.com/ClickHouse/ClickHouse/pull/4894) ([Vitaly Baranov](https://github.com/vitlibar))
-   Fix rare bug when setting `min_bytes_to_use_direct_io` is greater than zero, which occures when thread have to seek backward in column file. [#4897](https://github.com/ClickHouse/ClickHouse/pull/4897) ([alesapin](https://github.com/alesapin))
-   Fix wrong argument types for aggregate functions with `LowCardinality` arguments (fixes issue [#4919](https://github.com/ClickHouse/ClickHouse/issues/4919)). [#4922](https://github.com/ClickHouse/ClickHouse/pull/4922) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fix function `toISOWeek` result for year 1970. [#4988](https://github.com/ClickHouse/ClickHouse/pull/4988) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix `DROP`, `TRUNCATE` and `OPTIMIZE` queries duplication, when executed on `ON CLUSTER` for `ReplicatedMergeTree*` tables family. [#4991](https://github.com/ClickHouse/ClickHouse/pull/4991) ([alesapin](https://github.com/alesapin))

#### Improvements {#improvements-2}

-   Keep ordinary, `DEFAULT`, `MATERIALIZED` and `ALIAS` columns in a single list (fixes issue [#2867](https://github.com/ClickHouse/ClickHouse/issues/2867)). [#4707](https://github.com/ClickHouse/ClickHouse/pull/4707) ([Alex Zatelepin](https://github.com/ztlpn))

### ClickHouse Release 19.4.3.11, 2019-04-02 {#clickhouse-release-19-4-3-11-2019-04-02}

#### Bug Fixes {#bug-fixes-8}

-   Fix crash in `FULL/RIGHT JOIN` when we joining on nullable vs not nullable. [#4855](https://github.com/ClickHouse/ClickHouse/pull/4855) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix segmentation fault in `clickhouse-copier`. [#4835](https://github.com/ClickHouse/ClickHouse/pull/4835) ([proller](https://github.com/proller))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-11}

-   Add a way to launch clickhouse-server image from a custom user. [#4753](https://github.com/ClickHouse/ClickHouse/pull/4753) ([Mikhail f. Shiryaev](https://github.com/Felixoid))

### ClickHouse Release 19.4.2.7, 2019-03-30 {#clickhouse-release-19-4-2-7-2019-03-30}

#### Bug Fixes {#bug-fixes-9}

-   Fixed reading from `Array(LowCardinality)` column in rare case when column contained a long sequence of empty arrays. [#4850](https://github.com/ClickHouse/ClickHouse/pull/4850) ([Nikolai Kochetov](https://github.com/KochetovNicolai))

### ClickHouse Release 19.4.1.3, 2019-03-19 {#clickhouse-release-19-4-1-3-2019-03-19}

#### Bug Fixes {#bug-fixes-10}

-   Fixed remote queries which contain both `LIMIT BY` and `LIMIT`. Previously, if `LIMIT BY` and `LIMIT` were used for remote query, `LIMIT` could happen before `LIMIT BY`, which led to too filtered result. [#4708](https://github.com/ClickHouse/ClickHouse/pull/4708) ([Constantin S. Pan](https://github.com/kvap))

### ClickHouse Release 19.4.0.49, 2019-03-09 {#clickhouse-release-19-4-0-49-2019-03-09}

#### New Features {#new-features-5}

-   Added full support for `Protobuf` format (input and output, nested data structures). [#4174](https://github.com/ClickHouse/ClickHouse/pull/4174) [#4493](https://github.com/ClickHouse/ClickHouse/pull/4493) ([Vitaly Baranov](https://github.com/vitlibar))
-   Added bitmap functions with Roaring Bitmaps. [#4207](https://github.com/ClickHouse/ClickHouse/pull/4207) ([Andy Yang](https://github.com/andyyzh)) [#4568](https://github.com/ClickHouse/ClickHouse/pull/4568) ([Vitaly Baranov](https://github.com/vitlibar))
-   Parquet format support. [#4448](https://github.com/ClickHouse/ClickHouse/pull/4448) ([proller](https://github.com/proller))
-   N-gram distance was added for fuzzy string comparison. It is similar to q-gram metrics in R language. [#4466](https://github.com/ClickHouse/ClickHouse/pull/4466) ([Danila Kutenin](https://github.com/danlark1))
-   Combine rules for graphite rollup from dedicated aggregation and retention patterns. [#4426](https://github.com/ClickHouse/ClickHouse/pull/4426) ([Mikhail f. Shiryaev](https://github.com/Felixoid))
-   Added `max_execution_speed` and `max_execution_speed_bytes` to limit resource usage. Added `min_execution_speed_bytes` setting to complement the `min_execution_speed`. [#4430](https://github.com/ClickHouse/ClickHouse/pull/4430) ([Winter Zhang](https://github.com/zhang2014))
-   Implemented function `flatten`. [#4555](https://github.com/ClickHouse/ClickHouse/pull/4555) [#4409](https://github.com/ClickHouse/ClickHouse/pull/4409) ([alexey-milovidov](https://github.com/alexey-milovidov), [kzon](https://github.com/kzon))
-   Added functions `arrayEnumerateDenseRanked` and `arrayEnumerateUniqRanked` (it’s like `arrayEnumerateUniq` but allows to fine tune array depth to look inside multidimensional arrays). [#4475](https://github.com/ClickHouse/ClickHouse/pull/4475) ([proller](https://github.com/proller)) [#4601](https://github.com/ClickHouse/ClickHouse/pull/4601) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Multiple JOINS with some restrictions: no asterisks, no complex aliases in ON/WHERE/GROUP BY/… [#4462](https://github.com/ClickHouse/ClickHouse/pull/4462) ([Artem Zuikov](https://github.com/4ertus2))

#### Bug Fixes {#bug-fixes-11}

-   This release also contains all bug fixes from 19.3 and 19.1.
-   Fixed bug in data skipping indices: order of granules after INSERT was incorrect. [#4407](https://github.com/ClickHouse/ClickHouse/pull/4407) ([Nikita Vasilev](https://github.com/nikvas0))
-   Fixed `set` index for `Nullable` and `LowCardinality` columns. Before it, `set` index with `Nullable` or `LowCardinality` column led to error `Data type must be deserialized with multiple streams` while selecting. [#4594](https://github.com/ClickHouse/ClickHouse/pull/4594) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Correctly set update_time on full `executable` dictionary update. [#4551](https://github.com/ClickHouse/ClickHouse/pull/4551) ([Tema Novikov](https://github.com/temoon))
-   Fix broken progress bar in 19.3. [#4627](https://github.com/ClickHouse/ClickHouse/pull/4627) ([filimonov](https://github.com/filimonov))
-   Fixed inconsistent values of MemoryTracker when memory region was shrinked, in certain cases. [#4619](https://github.com/ClickHouse/ClickHouse/pull/4619) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed undefined behaviour in ThreadPool. [#4612](https://github.com/ClickHouse/ClickHouse/pull/4612) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed a very rare crash with the message `mutex lock failed: Invalid argument` that could happen when a MergeTree table was dropped concurrently with a SELECT. [#4608](https://github.com/ClickHouse/ClickHouse/pull/4608) ([Alex Zatelepin](https://github.com/ztlpn))
-   ODBC driver compatibility with `LowCardinality` data type. [#4381](https://github.com/ClickHouse/ClickHouse/pull/4381) ([proller](https://github.com/proller))
-   FreeBSD: Fixup for `AIOcontextPool: Found io_event with unknown id 0` error. [#4438](https://github.com/ClickHouse/ClickHouse/pull/4438) ([urgordeadbeef](https://github.com/urgordeadbeef))
-   `system.part_log` table was created regardless to configuration. [#4483](https://github.com/ClickHouse/ClickHouse/pull/4483) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix undefined behaviour in `dictIsIn` function for cache dictionaries. [#4515](https://github.com/ClickHouse/ClickHouse/pull/4515) ([alesapin](https://github.com/alesapin))
-   Fixed a deadlock when a SELECT query locks the same table multiple times (e.g. from different threads or when executing multiple subqueries) and there is a concurrent DDL query. [#4535](https://github.com/ClickHouse/ClickHouse/pull/4535) ([Alex Zatelepin](https://github.com/ztlpn))
-   Disable compile_expressions by default until we get own `llvm` contrib and can test it with `clang` and `asan`. [#4579](https://github.com/ClickHouse/ClickHouse/pull/4579) ([alesapin](https://github.com/alesapin))
-   Prevent `std::terminate` when `invalidate_query` for `clickhouse` external dictionary source has returned wrong resultset (empty or more than one row or more than one column). Fixed issue when the `invalidate_query` was performed every five seconds regardless to the `lifetime`. [#4583](https://github.com/ClickHouse/ClickHouse/pull/4583) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Avoid deadlock when the `invalidate_query` for a dictionary with `clickhouse` source was involving `system.dictionaries` table or `Dictionaries` database (rare case). [#4599](https://github.com/ClickHouse/ClickHouse/pull/4599) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixes for CROSS JOIN with empty WHERE. [#4598](https://github.com/ClickHouse/ClickHouse/pull/4598) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed segfault in function “replicate” when constant argument is passed. [#4603](https://github.com/ClickHouse/ClickHouse/pull/4603) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix lambda function with predicate optimizer. [#4408](https://github.com/ClickHouse/ClickHouse/pull/4408) ([Winter Zhang](https://github.com/zhang2014))
-   Multiple JOINs multiple fixes. [#4595](https://github.com/ClickHouse/ClickHouse/pull/4595) ([Artem Zuikov](https://github.com/4ertus2))

#### Improvements {#improvements-3}

-   Support aliases in JOIN ON section for right table columns. [#4412](https://github.com/ClickHouse/ClickHouse/pull/4412) ([Artem Zuikov](https://github.com/4ertus2))
-   Result of multiple JOINs need correct result names to be used in subselects. Replace flat aliases with source names in result. [#4474](https://github.com/ClickHouse/ClickHouse/pull/4474) ([Artem Zuikov](https://github.com/4ertus2))
-   Improve push-down logic for joined statements. [#4387](https://github.com/ClickHouse/ClickHouse/pull/4387) ([Ivan](https://github.com/abyss7))

#### Performance Improvements {#performance-improvements-3}

-   Improved heuristics of “move to PREWHERE” optimization. [#4405](https://github.com/ClickHouse/ClickHouse/pull/4405) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Use proper lookup tables that uses HashTable’s API for 8-bit and 16-bit keys. [#4536](https://github.com/ClickHouse/ClickHouse/pull/4536) ([Amos Bird](https://github.com/amosbird))
-   Improved performance of string comparison. [#4564](https://github.com/ClickHouse/ClickHouse/pull/4564) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Cleanup distributed DDL queue in a separate thread so that it does not slow down the main loop that processes distributed DDL tasks. [#4502](https://github.com/ClickHouse/ClickHouse/pull/4502) ([Alex Zatelepin](https://github.com/ztlpn))
-   When `min_bytes_to_use_direct_io` is set to 1, not every file was opened with O_DIRECT mode because the data size to read was sometimes underestimated by the size of one compressed block. [#4526](https://github.com/ClickHouse/ClickHouse/pull/4526) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-12}

-   Added support for clang-9 [#4604](https://github.com/ClickHouse/ClickHouse/pull/4604) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix wrong `__asm__` instructions (again) [#4621](https://github.com/ClickHouse/ClickHouse/pull/4621) ([Konstantin Podshumok](https://github.com/podshumok))
-   Add ability to specify settings for `clickhouse-performance-test` from command line. [#4437](https://github.com/ClickHouse/ClickHouse/pull/4437) ([alesapin](https://github.com/alesapin))
-   Add dictionaries tests to integration tests. [#4477](https://github.com/ClickHouse/ClickHouse/pull/4477) ([alesapin](https://github.com/alesapin))
-   Added queries from the benchmark on the website to automated performance tests. [#4496](https://github.com/ClickHouse/ClickHouse/pull/4496) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `xxhash.h` does not exist in external lz4 because it is an implementation detail and its symbols are namespaced with `XXH_NAMESPACE` macro. When lz4 is external, xxHash has to be external too, and the dependents have to link to it. [#4495](https://github.com/ClickHouse/ClickHouse/pull/4495) ([Orivej Desh](https://github.com/orivej))
-   Fixed a case when `quantileTiming` aggregate function can be called with negative or floating point argument (this fixes fuzz test with undefined behaviour sanitizer). [#4506](https://github.com/ClickHouse/ClickHouse/pull/4506) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Spelling error correction. [#4531](https://github.com/ClickHouse/ClickHouse/pull/4531) ([sdk2](https://github.com/sdk2))
-   Fix compilation on Mac. [#4371](https://github.com/ClickHouse/ClickHouse/pull/4371) ([Vitaly Baranov](https://github.com/vitlibar))
-   Build fixes for FreeBSD and various unusual build configurations. [#4444](https://github.com/ClickHouse/ClickHouse/pull/4444) ([proller](https://github.com/proller))

## ClickHouse Release 19.3 {#clickhouse-release-19-3}

### ClickHouse Release 19.3.9.1, 2019-04-02 {#clickhouse-release-19-3-9-1-2019-04-02}

#### Bug Fixes {#bug-fixes-12}

-   Fix crash in `FULL/RIGHT JOIN` when we joining on nullable vs not nullable. [#4855](https://github.com/ClickHouse/ClickHouse/pull/4855) ([Artem Zuikov](https://github.com/4ertus2))
-   Fix segmentation fault in `clickhouse-copier`. [#4835](https://github.com/ClickHouse/ClickHouse/pull/4835) ([proller](https://github.com/proller))
-   Fixed reading from `Array(LowCardinality)` column in rare case when column contained a long sequence of empty arrays. [#4850](https://github.com/ClickHouse/ClickHouse/pull/4850) ([Nikolai Kochetov](https://github.com/KochetovNicolai))

#### Build/Testing/Packaging Improvement {#buildtestingpackaging-improvement-13}

-   Add a way to launch clickhouse-server image from a custom user [#4753](https://github.com/ClickHouse/ClickHouse/pull/4753) ([Mikhail f. Shiryaev](https://github.com/Felixoid))

### ClickHouse Release 19.3.7, 2019-03-12 {#clickhouse-release-19-3-7-2019-03-12}

#### Bug Fixes {#bug-fixes-13}

-   Fixed error in #3920. This error manifests itself as random cache corruption (messages `Unknown codec family code`, `Cannot seek through file`) and segfaults. This bug first appeared in version 19.1 and is present in versions up to 19.1.10 and 19.3.6. [#4623](https://github.com/ClickHouse/ClickHouse/pull/4623) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.3.6, 2019-03-02 {#clickhouse-release-19-3-6-2019-03-02}

#### Bug Fixes {#bug-fixes-14}

-   When there are more than 1000 threads in a thread pool, `std::terminate` may happen on thread exit. [Azat Khuzhin](https://github.com/azat) [#4485](https://github.com/ClickHouse/ClickHouse/pull/4485) [#4505](https://github.com/ClickHouse/ClickHouse/pull/4505) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Now it’s possible to create `ReplicatedMergeTree*` tables with comments on columns without defaults and tables with columns codecs without comments and defaults. Also fix comparison of codecs. [#4523](https://github.com/ClickHouse/ClickHouse/pull/4523) ([alesapin](https://github.com/alesapin))
-   Fixed crash on JOIN with array or tuple. [#4552](https://github.com/ClickHouse/ClickHouse/pull/4552) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed crash in clickhouse-copier with the message `ThreadStatus not created`. [#4540](https://github.com/ClickHouse/ClickHouse/pull/4540) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed hangup on server shutdown if distributed DDLs were used. [#4472](https://github.com/ClickHouse/ClickHouse/pull/4472) ([Alex Zatelepin](https://github.com/ztlpn))
-   Incorrect column numbers were printed in error message about text format parsing for columns with number greater than 10. [#4484](https://github.com/ClickHouse/ClickHouse/pull/4484) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements-3}

-   Fixed build with AVX enabled. [#4527](https://github.com/ClickHouse/ClickHouse/pull/4527) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Enable extended accounting and IO accounting based on good known version instead of kernel under which it is compiled. [#4541](https://github.com/ClickHouse/ClickHouse/pull/4541) ([nvartolomei](https://github.com/nvartolomei))
-   Allow to skip setting of core_dump.size_limit, warning instead of throw if limit set fail. [#4473](https://github.com/ClickHouse/ClickHouse/pull/4473) ([proller](https://github.com/proller))
-   Removed the `inline` tags of `void readBinary(...)` in `Field.cpp`. Also merged redundant `namespace DB` blocks. [#4530](https://github.com/ClickHouse/ClickHouse/pull/4530) ([hcz](https://github.com/hczhcz))

### ClickHouse Release 19.3.5, 2019-02-21 {#clickhouse-release-19-3-5-2019-02-21}

#### Bug Fixes {#bug-fixes-15}

-   Fixed bug with large http insert queries processing. [#4454](https://github.com/ClickHouse/ClickHouse/pull/4454) ([alesapin](https://github.com/alesapin))
-   Fixed backward incompatibility with old versions due to wrong implementation of `send_logs_level` setting. [#4445](https://github.com/ClickHouse/ClickHouse/pull/4445) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed backward incompatibility of table function `remote` introduced with column comments. [#4446](https://github.com/ClickHouse/ClickHouse/pull/4446) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.3.4, 2019-02-16 {#clickhouse-release-19-3-4-2019-02-16}

#### Improvements {#improvements-4}

-   Table index size is not accounted for memory limits when doing `ATTACH TABLE` query. Avoided the possibility that a table cannot be attached after being detached. [#4396](https://github.com/ClickHouse/ClickHouse/pull/4396) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Slightly raised up the limit on max string and array size received from ZooKeeper. It allows to continue to work with increased size of `CLIENT_JVMFLAGS=-Djute.maxbuffer=...` on ZooKeeper. [#4398](https://github.com/ClickHouse/ClickHouse/pull/4398) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Allow to repair abandoned replica even if it already has huge number of nodes in its queue. [#4399](https://github.com/ClickHouse/ClickHouse/pull/4399) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Add one required argument to `SET` index (max stored rows number). [#4386](https://github.com/ClickHouse/ClickHouse/pull/4386) ([Nikita Vasilev](https://github.com/nikvas0))

#### Bug Fixes {#bug-fixes-16}

-   Fixed `WITH ROLLUP` result for group by single `LowCardinality` key. [#4384](https://github.com/ClickHouse/ClickHouse/pull/4384) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Fixed bug in the set index (dropping a granule if it contains more than `max_rows` rows). [#4386](https://github.com/ClickHouse/ClickHouse/pull/4386) ([Nikita Vasilev](https://github.com/nikvas0))
-   A lot of FreeBSD build fixes. [#4397](https://github.com/ClickHouse/ClickHouse/pull/4397) ([proller](https://github.com/proller))
-   Fixed aliases substitution in queries with subquery containing same alias (issue [#4110](https://github.com/ClickHouse/ClickHouse/issues/4110)). [#4351](https://github.com/ClickHouse/ClickHouse/pull/4351) ([Artem Zuikov](https://github.com/4ertus2))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements-4}

-   Add ability to run `clickhouse-server` for stateless tests in docker image. [#4347](https://github.com/ClickHouse/ClickHouse/pull/4347) ([Vasily Nemkov](https://github.com/Enmk))

### ClickHouse Release 19.3.3, 2019-02-13 {#clickhouse-release-19-3-3-2019-02-13}

#### New Features {#new-features-6}

-   Added the `KILL MUTATION` statement that allows removing mutations that are for some reasons stuck. Added `latest_failed_part`, `latest_fail_time`, `latest_fail_reason` fields to the `system.mutations` table for easier troubleshooting. [#4287](https://github.com/ClickHouse/ClickHouse/pull/4287) ([Alex Zatelepin](https://github.com/ztlpn))
-   Added aggregate function `entropy` which computes Shannon entropy. [#4238](https://github.com/ClickHouse/ClickHouse/pull/4238) ([Quid37](https://github.com/Quid37))
-   Added ability to send queries `INSERT INTO tbl VALUES (....` to server without splitting on `query` and `data` parts. [#4301](https://github.com/ClickHouse/ClickHouse/pull/4301) ([alesapin](https://github.com/alesapin))
-   Generic implementation of `arrayWithConstant` function was added. [#4322](https://github.com/ClickHouse/ClickHouse/pull/4322) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Implemented `NOT BETWEEN` comparison operator. [#4228](https://github.com/ClickHouse/ClickHouse/pull/4228) ([Dmitry Naumov](https://github.com/nezed))
-   Implement `sumMapFiltered` in order to be able to limit the number of keys for which values will be summed by `sumMap`. [#4129](https://github.com/ClickHouse/ClickHouse/pull/4129) ([Léo Ercolanelli](https://github.com/ercolanelli-leo))
-   Added support of `Nullable` types in `mysql` table function. [#4198](https://github.com/ClickHouse/ClickHouse/pull/4198) ([Emmanuel Donin de Rosière](https://github.com/edonin))
-   Support for arbitrary constant expressions in `LIMIT` clause. [#4246](https://github.com/ClickHouse/ClickHouse/pull/4246) ([k3box](https://github.com/k3box))
-   Added `topKWeighted` aggregate function that takes additional argument with (unsigned integer) weight. [#4245](https://github.com/ClickHouse/ClickHouse/pull/4245) ([Andrew Golman](https://github.com/andrewgolman))
-   `StorageJoin` now supports `join_any_take_last_row` setting that allows overwriting existing values of the same key. [#3973](https://github.com/ClickHouse/ClickHouse/pull/3973) ([Amos Bird](https://github.com/amosbird)
-   Added function `toStartOfInterval`. [#4304](https://github.com/ClickHouse/ClickHouse/pull/4304) ([Vitaly Baranov](https://github.com/vitlibar))
-   Added `RowBinaryWithNamesAndTypes` format. [#4200](https://github.com/ClickHouse/ClickHouse/pull/4200) ([Oleg V. Kozlyuk](https://github.com/DarkWanderer))
-   Added `IPv4` and `IPv6` data types. More effective implementations of `IPv*` functions. [#3669](https://github.com/ClickHouse/ClickHouse/pull/3669) ([Vasily Nemkov](https://github.com/Enmk))
-   Added function `toStartOfTenMinutes()`. [#4298](https://github.com/ClickHouse/ClickHouse/pull/4298) ([Vitaly Baranov](https://github.com/vitlibar))
-   Added `Protobuf` output format. [#4005](https://github.com/ClickHouse/ClickHouse/pull/4005) [#4158](https://github.com/ClickHouse/ClickHouse/pull/4158) ([Vitaly Baranov](https://github.com/vitlibar))
-   Added brotli support for HTTP interface for data import (INSERTs). [#4235](https://github.com/ClickHouse/ClickHouse/pull/4235) ([Mikhail](https://github.com/fandyushin))
-   Added hints while user make typo in function name or type in command line client. [#4239](https://github.com/ClickHouse/ClickHouse/pull/4239) ([Danila Kutenin](https://github.com/danlark1))
-   Added `Query-Id` to Server’s HTTP Response header. [#4231](https://github.com/ClickHouse/ClickHouse/pull/4231) ([Mikhail](https://github.com/fandyushin))

#### Experimental Features {#experimental-features-2}

-   Added `minmax` and `set` data skipping indices for MergeTree table engines family. [#4143](https://github.com/ClickHouse/ClickHouse/pull/4143) ([Nikita Vasilev](https://github.com/nikvas0))
-   Added conversion of `CROSS JOIN` to `INNER JOIN` if possible. [#4221](https://github.com/ClickHouse/ClickHouse/pull/4221) [#4266](https://github.com/ClickHouse/ClickHouse/pull/4266) ([Artem Zuikov](https://github.com/4ertus2))

#### Bug Fixes {#bug-fixes-17}

-   Fixed `Not found column` for duplicate columns in `JOIN ON` section. [#4279](https://github.com/ClickHouse/ClickHouse/pull/4279) ([Artem Zuikov](https://github.com/4ertus2))
-   Make `START REPLICATED SENDS` command start replicated sends. [#4229](https://github.com/ClickHouse/ClickHouse/pull/4229) ([nvartolomei](https://github.com/nvartolomei))
-   Fixed aggregate functions execution with `Array(LowCardinality)` arguments. [#4055](https://github.com/ClickHouse/ClickHouse/pull/4055) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Fixed wrong behaviour when doing `INSERT ... SELECT ... FROM file(...)` query and file has `CSVWithNames` or `TSVWIthNames` format and the first data row is missing. [#4297](https://github.com/ClickHouse/ClickHouse/pull/4297) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed crash on dictionary reload if dictionary not available. This bug was appeared in 19.1.6. [#4188](https://github.com/ClickHouse/ClickHouse/pull/4188) ([proller](https://github.com/proller))
-   Fixed `ALL JOIN` with duplicates in right table. [#4184](https://github.com/ClickHouse/ClickHouse/pull/4184) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed segmentation fault with `use_uncompressed_cache=1` and exception with wrong uncompressed size. This bug was appeared in 19.1.6. [#4186](https://github.com/ClickHouse/ClickHouse/pull/4186) ([alesapin](https://github.com/alesapin))
-   Fixed `compile_expressions` bug with comparison of big (more than int16) dates. [#4341](https://github.com/ClickHouse/ClickHouse/pull/4341) ([alesapin](https://github.com/alesapin))
-   Fixed infinite loop when selecting from table function `numbers(0)`. [#4280](https://github.com/ClickHouse/ClickHouse/pull/4280) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Temporarily disable predicate optimization for `ORDER BY`. [#3890](https://github.com/ClickHouse/ClickHouse/pull/3890) ([Winter Zhang](https://github.com/zhang2014))
-   Fixed `Illegal instruction` error when using base64 functions on old CPUs. This error has been reproduced only when ClickHouse was compiled with gcc-8. [#4275](https://github.com/ClickHouse/ClickHouse/pull/4275) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed `No message received` error when interacting with PostgreSQL ODBC Driver through TLS connection. Also fixes segfault when using MySQL ODBC Driver. [#4170](https://github.com/ClickHouse/ClickHouse/pull/4170) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed incorrect result when `Date` and `DateTime` arguments are used in branches of conditional operator (function `if`). Added generic case for function `if`. [#4243](https://github.com/ClickHouse/ClickHouse/pull/4243) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   ClickHouse dictionaries now load within `clickhouse` process. [#4166](https://github.com/ClickHouse/ClickHouse/pull/4166) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed deadlock when `SELECT` from a table with `File` engine was retried after `No such file or directory` error. [#4161](https://github.com/ClickHouse/ClickHouse/pull/4161) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed race condition when selecting from `system.tables` may give `table does not exist` error. [#4313](https://github.com/ClickHouse/ClickHouse/pull/4313) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `clickhouse-client` can segfault on exit while loading data for command line suggestions if it was run in interactive mode. [#4317](https://github.com/ClickHouse/ClickHouse/pull/4317) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed a bug when the execution of mutations containing `IN` operators was producing incorrect results. [#4099](https://github.com/ClickHouse/ClickHouse/pull/4099) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fixed error: if there is a database with `Dictionary` engine, all dictionaries forced to load at server startup, and if there is a dictionary with ClickHouse source from localhost, the dictionary cannot load. [#4255](https://github.com/ClickHouse/ClickHouse/pull/4255) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed error when system logs are tried to create again at server shutdown. [#4254](https://github.com/ClickHouse/ClickHouse/pull/4254) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Correctly return the right type and properly handle locks in `joinGet` function. [#4153](https://github.com/ClickHouse/ClickHouse/pull/4153) ([Amos Bird](https://github.com/amosbird))
-   Added `sumMapWithOverflow` function. [#4151](https://github.com/ClickHouse/ClickHouse/pull/4151) ([Léo Ercolanelli](https://github.com/ercolanelli-leo))
-   Fixed segfault with `allow_experimental_multiple_joins_emulation`. [52de2c](https://github.com/ClickHouse/ClickHouse/commit/52de2cd927f7b5257dd67e175f0a5560a48840d0) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed bug with incorrect `Date` and `DateTime` comparison. [#4237](https://github.com/ClickHouse/ClickHouse/pull/4237) ([valexey](https://github.com/valexey))
-   Fixed fuzz test under undefined behavior sanitizer: added parameter type check for `quantile*Weighted` family of functions. [#4145](https://github.com/ClickHouse/ClickHouse/pull/4145) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed rare race condition when removing of old data parts can fail with `File not found` error. [#4378](https://github.com/ClickHouse/ClickHouse/pull/4378) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix install package with missing /etc/clickhouse-server/config.xml. [#4343](https://github.com/ClickHouse/ClickHouse/pull/4343) ([proller](https://github.com/proller))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements-5}

-   Debian package: correct /etc/clickhouse-server/preprocessed link according to config. [#4205](https://github.com/ClickHouse/ClickHouse/pull/4205) ([proller](https://github.com/proller))
-   Various build fixes for FreeBSD. [#4225](https://github.com/ClickHouse/ClickHouse/pull/4225) ([proller](https://github.com/proller))
-   Added ability to create, fill and drop tables in perftest. [#4220](https://github.com/ClickHouse/ClickHouse/pull/4220) ([alesapin](https://github.com/alesapin))
-   Added a script to check for duplicate includes. [#4326](https://github.com/ClickHouse/ClickHouse/pull/4326) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added ability to run queries by index in performance test. [#4264](https://github.com/ClickHouse/ClickHouse/pull/4264) ([alesapin](https://github.com/alesapin))
-   Package with debug symbols is suggested to be installed. [#4274](https://github.com/ClickHouse/ClickHouse/pull/4274) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Refactoring of performance-test. Better logging and signals handling. [#4171](https://github.com/ClickHouse/ClickHouse/pull/4171) ([alesapin](https://github.com/alesapin))
-   Added docs to anonymized Yandex.Metrika datasets. [#4164](https://github.com/ClickHouse/ClickHouse/pull/4164) ([alesapin](https://github.com/alesapin))
-   Аdded tool for converting an old month-partitioned part to the custom-partitioned format. [#4195](https://github.com/ClickHouse/ClickHouse/pull/4195) ([Alex Zatelepin](https://github.com/ztlpn))
-   Added docs about two datasets in s3. [#4144](https://github.com/ClickHouse/ClickHouse/pull/4144) ([alesapin](https://github.com/alesapin))
-   Added script which creates changelog from pull requests description. [#4169](https://github.com/ClickHouse/ClickHouse/pull/4169) [#4173](https://github.com/ClickHouse/ClickHouse/pull/4173) ([KochetovNicolai](https://github.com/KochetovNicolai)) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Added puppet module for ClickHouse. [#4182](https://github.com/ClickHouse/ClickHouse/pull/4182) ([Maxim Fedotov](https://github.com/MaxFedotov))
-   Added docs for a group of undocumented functions. [#4168](https://github.com/ClickHouse/ClickHouse/pull/4168) ([Winter Zhang](https://github.com/zhang2014))
-   ARM build fixes. [#4210](https://github.com/ClickHouse/ClickHouse/pull/4210)[#4306](https://github.com/ClickHouse/ClickHouse/pull/4306) [#4291](https://github.com/ClickHouse/ClickHouse/pull/4291) ([proller](https://github.com/proller)) ([proller](https://github.com/proller))
-   Dictionary tests now able to run from `ctest`. [#4189](https://github.com/ClickHouse/ClickHouse/pull/4189) ([proller](https://github.com/proller))
-   Now `/etc/ssl` is used as default directory with SSL certificates. [#4167](https://github.com/ClickHouse/ClickHouse/pull/4167) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added checking SSE and AVX instruction at start. [#4234](https://github.com/ClickHouse/ClickHouse/pull/4234) ([Igr](https://github.com/igron99))
-   Init script will wait server until start. [#4281](https://github.com/ClickHouse/ClickHouse/pull/4281) ([proller](https://github.com/proller))

#### Backward Incompatible Changes {#backward-incompatible-changes-1}

-   Removed `allow_experimental_low_cardinality_type` setting. `LowCardinality` data types are production ready. [#4323](https://github.com/ClickHouse/ClickHouse/pull/4323) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Reduce mark cache size and uncompressed cache size accordingly to available memory amount. [#4240](https://github.com/ClickHouse/ClickHouse/pull/4240) ([Lopatin Konstantin](https://github.com/k-lopatin)
-   Added keyword `INDEX` in `CREATE TABLE` query. A column with name `index` must be quoted with backticks or double quotes: `` `index` ``. [#4143](https://github.com/ClickHouse/ClickHouse/pull/4143) ([Nikita Vasilev](https://github.com/nikvas0))
-   `sumMap` now promote result type instead of overflow. The old `sumMap` behavior can be obtained by using `sumMapWithOverflow` function. [#4151](https://github.com/ClickHouse/ClickHouse/pull/4151) ([Léo Ercolanelli](https://github.com/ercolanelli-leo))

#### Performance Improvements {#performance-improvements-4}

-   `std::sort` replaced by `pdqsort` for queries without `LIMIT`. [#4236](https://github.com/ClickHouse/ClickHouse/pull/4236) ([Evgenii Pravda](https://github.com/kvinty))
-   Now server reuse threads from global thread pool. This affects performance in some corner cases. [#4150](https://github.com/ClickHouse/ClickHouse/pull/4150) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Improvements {#improvements-5}

-   Implemented AIO support for FreeBSD. [#4305](https://github.com/ClickHouse/ClickHouse/pull/4305) ([urgordeadbeef](https://github.com/urgordeadbeef))
-   `SELECT * FROM a JOIN b USING a, b` now return `a` and `b` columns only from the left table. [#4141](https://github.com/ClickHouse/ClickHouse/pull/4141) ([Artem Zuikov](https://github.com/4ertus2))
-   Allow `-C` option of client to work as `-c` option. [#4232](https://github.com/ClickHouse/ClickHouse/pull/4232) ([syominsergey](https://github.com/syominsergey))
-   Now option `--password` used without value requires password from stdin. [#4230](https://github.com/ClickHouse/ClickHouse/pull/4230) ([BSD_Conqueror](https://github.com/bsd-conqueror))
-   Added highlighting of unescaped metacharacters in string literals that contain `LIKE` expressions or regexps. [#4327](https://github.com/ClickHouse/ClickHouse/pull/4327) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added cancelling of HTTP read only queries if client socket goes away. [#4213](https://github.com/ClickHouse/ClickHouse/pull/4213) ([nvartolomei](https://github.com/nvartolomei))
-   Now server reports progress to keep client connections alive. [#4215](https://github.com/ClickHouse/ClickHouse/pull/4215) ([Ivan](https://github.com/abyss7))
-   Slightly better message with reason for OPTIMIZE query with `optimize_throw_if_noop` setting enabled. [#4294](https://github.com/ClickHouse/ClickHouse/pull/4294) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added support of `--version` option for clickhouse server. [#4251](https://github.com/ClickHouse/ClickHouse/pull/4251) ([Lopatin Konstantin](https://github.com/k-lopatin))
-   Added `--help/-h` option to `clickhouse-server`. [#4233](https://github.com/ClickHouse/ClickHouse/pull/4233) ([Yuriy Baranov](https://github.com/yurriy))
-   Added support for scalar subqueries with aggregate function state result. [#4348](https://github.com/ClickHouse/ClickHouse/pull/4348) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
-   Improved server shutdown time and ALTERs waiting time. [#4372](https://github.com/ClickHouse/ClickHouse/pull/4372) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added info about the replicated_can_become_leader setting to system.replicas and add logging if the replica won’t try to become leader. [#4379](https://github.com/ClickHouse/ClickHouse/pull/4379) ([Alex Zatelepin](https://github.com/ztlpn))

## ClickHouse Release 19.1 {#clickhouse-release-19-1}

### ClickHouse Release 19.1.14, 2019-03-14 {#clickhouse-release-19-1-14-2019-03-14}

-   Fixed error `Column ... queried more than once` that may happen if the setting `asterisk_left_columns_only` is set to 1 in case of using `GLOBAL JOIN` with `SELECT *` (rare case). The issue does not exist in 19.3 and newer. [6bac7d8d](https://github.com/ClickHouse/ClickHouse/pull/4692/commits/6bac7d8d11a9b0d6de0b32b53c47eb2f6f8e7062) ([Artem Zuikov](https://github.com/4ertus2))

### ClickHouse Release 19.1.13, 2019-03-12 {#clickhouse-release-19-1-13-2019-03-12}

This release contains exactly the same set of patches as 19.3.7.

### ClickHouse Release 19.1.10, 2019-03-03 {#clickhouse-release-19-1-10-2019-03-03}

This release contains exactly the same set of patches as 19.3.6.

## ClickHouse Release 19.1 {#clickhouse-release-19-1-1}

### ClickHouse Release 19.1.9, 2019-02-21 {#clickhouse-release-19-1-9-2019-02-21}

#### Bug Fixes {#bug-fixes-18}

-   Fixed backward incompatibility with old versions due to wrong implementation of `send_logs_level` setting. [#4445](https://github.com/ClickHouse/ClickHouse/pull/4445) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed backward incompatibility of table function `remote` introduced with column comments. [#4446](https://github.com/ClickHouse/ClickHouse/pull/4446) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.1.8, 2019-02-16 {#clickhouse-release-19-1-8-2019-02-16}

#### Bug Fixes {#bug-fixes-19}

-   Fix install package with missing /etc/clickhouse-server/config.xml. [#4343](https://github.com/ClickHouse/ClickHouse/pull/4343) ([proller](https://github.com/proller))

## ClickHouse Release 19.1 {#clickhouse-release-19-1-2}

### ClickHouse Release 19.1.7, 2019-02-15 {#clickhouse-release-19-1-7-2019-02-15}

#### Bug Fixes {#bug-fixes-20}

-   Correctly return the right type and properly handle locks in `joinGet` function. [#4153](https://github.com/ClickHouse/ClickHouse/pull/4153) ([Amos Bird](https://github.com/amosbird))
-   Fixed error when system logs are tried to create again at server shutdown. [#4254](https://github.com/ClickHouse/ClickHouse/pull/4254) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed error: if there is a database with `Dictionary` engine, all dictionaries forced to load at server startup, and if there is a dictionary with ClickHouse source from localhost, the dictionary cannot load. [#4255](https://github.com/ClickHouse/ClickHouse/pull/4255) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed a bug when the execution of mutations containing `IN` operators was producing incorrect results. [#4099](https://github.com/ClickHouse/ClickHouse/pull/4099) ([Alex Zatelepin](https://github.com/ztlpn))
-   `clickhouse-client` can segfault on exit while loading data for command line suggestions if it was run in interactive mode. [#4317](https://github.com/ClickHouse/ClickHouse/pull/4317) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed race condition when selecting from `system.tables` may give `table does not exist` error. [#4313](https://github.com/ClickHouse/ClickHouse/pull/4313) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed deadlock when `SELECT` from a table with `File` engine was retried after `No such file or directory` error. [#4161](https://github.com/ClickHouse/ClickHouse/pull/4161) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed an issue: local ClickHouse dictionaries are loaded via TCP, but should load within process. [#4166](https://github.com/ClickHouse/ClickHouse/pull/4166) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed `No message received` error when interacting with PostgreSQL ODBC Driver through TLS connection. Also fixes segfault when using MySQL ODBC Driver. [#4170](https://github.com/ClickHouse/ClickHouse/pull/4170) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Temporarily disable predicate optimization for `ORDER BY`. [#3890](https://github.com/ClickHouse/ClickHouse/pull/3890) ([Winter Zhang](https://github.com/zhang2014))
-   Fixed infinite loop when selecting from table function `numbers(0)`. [#4280](https://github.com/ClickHouse/ClickHouse/pull/4280) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed `compile_expressions` bug with comparison of big (more than int16) dates. [#4341](https://github.com/ClickHouse/ClickHouse/pull/4341) ([alesapin](https://github.com/alesapin))
-   Fixed segmentation fault with `uncompressed_cache=1` and exception with wrong uncompressed size. [#4186](https://github.com/ClickHouse/ClickHouse/pull/4186) ([alesapin](https://github.com/alesapin))
-   Fixed `ALL JOIN` with duplicates in right table. [#4184](https://github.com/ClickHouse/ClickHouse/pull/4184) ([Artem Zuikov](https://github.com/4ertus2))
-   Fixed wrong behaviour when doing `INSERT ... SELECT ... FROM file(...)` query and file has `CSVWithNames` or `TSVWIthNames` format and the first data row is missing. [#4297](https://github.com/ClickHouse/ClickHouse/pull/4297) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed aggregate functions execution with `Array(LowCardinality)` arguments. [#4055](https://github.com/ClickHouse/ClickHouse/pull/4055) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Debian package: correct /etc/clickhouse-server/preprocessed link according to config. [#4205](https://github.com/ClickHouse/ClickHouse/pull/4205) ([proller](https://github.com/proller))
-   Fixed fuzz test under undefined behavior sanitizer: added parameter type check for `quantile*Weighted` family of functions. [#4145](https://github.com/ClickHouse/ClickHouse/pull/4145) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Make `START REPLICATED SENDS` command start replicated sends. [#4229](https://github.com/ClickHouse/ClickHouse/pull/4229) ([nvartolomei](https://github.com/nvartolomei))
-   Fixed `Not found column` for duplicate columns in JOIN ON section. [#4279](https://github.com/ClickHouse/ClickHouse/pull/4279) ([Artem Zuikov](https://github.com/4ertus2))
-   Now `/etc/ssl` is used as default directory with SSL certificates. [#4167](https://github.com/ClickHouse/ClickHouse/pull/4167) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed crash on dictionary reload if dictionary not available. [#4188](https://github.com/ClickHouse/ClickHouse/pull/4188) ([proller](https://github.com/proller))
-   Fixed bug with incorrect `Date` and `DateTime` comparison. [#4237](https://github.com/ClickHouse/ClickHouse/pull/4237) ([valexey](https://github.com/valexey))
-   Fixed incorrect result when `Date` and `DateTime` arguments are used in branches of conditional operator (function `if`). Added generic case for function `if`. [#4243](https://github.com/ClickHouse/ClickHouse/pull/4243) ([alexey-milovidov](https://github.com/alexey-milovidov))

### ClickHouse Release 19.1.6, 2019-01-24 {#clickhouse-release-19-1-6-2019-01-24}

#### New Features {#new-features-7}

-   Custom per column compression codecs for tables. [#3899](https://github.com/ClickHouse/ClickHouse/pull/3899) [#4111](https://github.com/ClickHouse/ClickHouse/pull/4111) ([alesapin](https://github.com/alesapin), [Winter Zhang](https://github.com/zhang2014), [Anatoly](https://github.com/Sindbag))
-   Added compression codec `Delta`. [#4052](https://github.com/ClickHouse/ClickHouse/pull/4052) ([alesapin](https://github.com/alesapin))
-   Allow to `ALTER` compression codecs. [#4054](https://github.com/ClickHouse/ClickHouse/pull/4054) ([alesapin](https://github.com/alesapin))
-   Added functions `left`, `right`, `trim`, `ltrim`, `rtrim`, `timestampadd`, `timestampsub` for SQL standard compatibility. [#3826](https://github.com/ClickHouse/ClickHouse/pull/3826) ([Ivan Blinkov](https://github.com/blinkov))
-   Support for write in `HDFS` tables and `hdfs` table function. [#4084](https://github.com/ClickHouse/ClickHouse/pull/4084) ([alesapin](https://github.com/alesapin))
-   Added functions to search for multiple constant strings from big haystack: `multiPosition`, `multiSearch` ,`firstMatch` also with `-UTF8`, `-CaseInsensitive`, and `-CaseInsensitiveUTF8` variants. [#4053](https://github.com/ClickHouse/ClickHouse/pull/4053) ([Danila Kutenin](https://github.com/danlark1))
-   Pruning of unused shards if `SELECT` query filters by sharding key (setting `optimize_skip_unused_shards`). [#3851](https://github.com/ClickHouse/ClickHouse/pull/3851) ([Gleb Kanterov](https://github.com/kanterov), [Ivan](https://github.com/abyss7))
-   Allow `Kafka` engine to ignore some number of parsing errors per block. [#4094](https://github.com/ClickHouse/ClickHouse/pull/4094) ([Ivan](https://github.com/abyss7))
-   Added support for `CatBoost` multiclass models evaluation. Function `modelEvaluate` returns tuple with per-class raw predictions for multiclass models. `libcatboostmodel.so` should be built with [#607](https://github.com/catboost/catboost/pull/607). [#3959](https://github.com/ClickHouse/ClickHouse/pull/3959) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Added functions `filesystemAvailable`, `filesystemFree`, `filesystemCapacity`. [#4097](https://github.com/ClickHouse/ClickHouse/pull/4097) ([Boris Granveaud](https://github.com/bgranvea))
-   Added hashing functions `xxHash64` and `xxHash32`. [#3905](https://github.com/ClickHouse/ClickHouse/pull/3905) ([filimonov](https://github.com/filimonov))
-   Added `gccMurmurHash` hashing function (GCC flavoured Murmur hash) which uses the same hash seed as [gcc](https://github.com/gcc-mirror/gcc/blob/41d6b10e96a1de98e90a7c0378437c3255814b16/libstdc%2B%2B-v3/include/bits/functional_hash.h#L191) [#4000](https://github.com/ClickHouse/ClickHouse/pull/4000) ([sundyli](https://github.com/sundy-li))
-   Added hashing functions `javaHash`, `hiveHash`. [#3811](https://github.com/ClickHouse/ClickHouse/pull/3811) ([shangshujie365](https://github.com/shangshujie365))
-   Added table function `remoteSecure`. Function works as `remote`, but uses secure connection. [#4088](https://github.com/ClickHouse/ClickHouse/pull/4088) ([proller](https://github.com/proller))

#### Experimental Features {#experimental-features-3}

-   Added multiple JOINs emulation (`allow_experimental_multiple_joins_emulation` setting). [#3946](https://github.com/ClickHouse/ClickHouse/pull/3946) ([Artem Zuikov](https://github.com/4ertus2))

#### Bug Fixes {#bug-fixes-21}

-   Make `compiled_expression_cache_size` setting limited by default to lower memory consumption. [#4041](https://github.com/ClickHouse/ClickHouse/pull/4041) ([alesapin](https://github.com/alesapin))
-   Fix a bug that led to hangups in threads that perform ALTERs of Replicated tables and in the thread that updates configuration from ZooKeeper. [#2947](https://github.com/ClickHouse/ClickHouse/issues/2947) [#3891](https://github.com/ClickHouse/ClickHouse/issues/3891) [#3934](https://github.com/ClickHouse/ClickHouse/pull/3934) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fixed a race condition when executing a distributed ALTER task. The race condition led to more than one replica trying to execute the task and all replicas except one failing with a ZooKeeper error. [#3904](https://github.com/ClickHouse/ClickHouse/pull/3904) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fix a bug when `from_zk` config elements weren’t refreshed after a request to ZooKeeper timed out. [#2947](https://github.com/ClickHouse/ClickHouse/issues/2947) [#3947](https://github.com/ClickHouse/ClickHouse/pull/3947) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fix bug with wrong prefix for IPv4 subnet masks. [#3945](https://github.com/ClickHouse/ClickHouse/pull/3945) ([alesapin](https://github.com/alesapin))
-   Fixed crash (`std::terminate`) in rare cases when a new thread cannot be created due to exhausted resources. [#3956](https://github.com/ClickHouse/ClickHouse/pull/3956) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix bug when in `remote` table function execution when wrong restrictions were used for in `getStructureOfRemoteTable`. [#4009](https://github.com/ClickHouse/ClickHouse/pull/4009) ([alesapin](https://github.com/alesapin))
-   Fix a leak of netlink sockets. They were placed in a pool where they were never deleted and new sockets were created at the start of a new thread when all current sockets were in use. [#4017](https://github.com/ClickHouse/ClickHouse/pull/4017) ([Alex Zatelepin](https://github.com/ztlpn))
-   Fix bug with closing `/proc/self/fd` directory earlier than all fds were read from `/proc` after forking `odbc-bridge` subprocess. [#4120](https://github.com/ClickHouse/ClickHouse/pull/4120) ([alesapin](https://github.com/alesapin))
-   Fixed String to UInt monotonic conversion in case of usage String in primary key. [#3870](https://github.com/ClickHouse/ClickHouse/pull/3870) ([Winter Zhang](https://github.com/zhang2014))
-   Fixed error in calculation of integer conversion function monotonicity. [#3921](https://github.com/ClickHouse/ClickHouse/pull/3921) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed segfault in `arrayEnumerateUniq`, `arrayEnumerateDense` functions in case of some invalid arguments. [#3909](https://github.com/ClickHouse/ClickHouse/pull/3909) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fix UB in StorageMerge. [#3910](https://github.com/ClickHouse/ClickHouse/pull/3910) ([Amos Bird](https://github.com/amosbird))
-   Fixed segfault in functions `addDays`, `subtractDays`. [#3913](https://github.com/ClickHouse/ClickHouse/pull/3913) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed error: functions `round`, `floor`, `trunc`, `ceil` may return bogus result when executed on integer argument and large negative scale. [#3914](https://github.com/ClickHouse/ClickHouse/pull/3914) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed a bug induced by ‘kill query sync’ which leads to a core dump. [#3916](https://github.com/ClickHouse/ClickHouse/pull/3916) ([muVulDeePecker](https://github.com/fancyqlx))
-   Fix bug with long delay after empty replication queue. [#3928](https://github.com/ClickHouse/ClickHouse/pull/3928) [#3932](https://github.com/ClickHouse/ClickHouse/pull/3932) ([alesapin](https://github.com/alesapin))
-   Fixed excessive memory usage in case of inserting into table with `LowCardinality` primary key. [#3955](https://github.com/ClickHouse/ClickHouse/pull/3955) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Fixed `LowCardinality` serialization for `Native` format in case of empty arrays. [#3907](https://github.com/ClickHouse/ClickHouse/issues/3907) [#4011](https://github.com/ClickHouse/ClickHouse/pull/4011) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Fixed incorrect result while using distinct by single LowCardinality numeric column. [#3895](https://github.com/ClickHouse/ClickHouse/issues/3895) [#4012](https://github.com/ClickHouse/ClickHouse/pull/4012) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Fixed specialized aggregation with LowCardinality key (in case when `compile` setting is enabled). [#3886](https://github.com/ClickHouse/ClickHouse/pull/3886) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Fix user and password forwarding for replicated tables queries. [#3957](https://github.com/ClickHouse/ClickHouse/pull/3957) ([alesapin](https://github.com/alesapin)) ([小路](https://github.com/nicelulu))
-   Fixed very rare race condition that can happen when listing tables in Dictionary database while reloading dictionaries. [#3970](https://github.com/ClickHouse/ClickHouse/pull/3970) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed incorrect result when HAVING was used with ROLLUP or CUBE. [#3756](https://github.com/ClickHouse/ClickHouse/issues/3756) [#3837](https://github.com/ClickHouse/ClickHouse/pull/3837) ([Sam Chou](https://github.com/reflection))
-   Fixed column aliases for query with `JOIN ON` syntax and distributed tables. [#3980](https://github.com/ClickHouse/ClickHouse/pull/3980) ([Winter Zhang](https://github.com/zhang2014))
-   Fixed error in internal implementation of `quantileTDigest` (found by Artem Vakhrushev). This error never happens in ClickHouse and was relevant only for those who use ClickHouse codebase as a library directly. [#3935](https://github.com/ClickHouse/ClickHouse/pull/3935) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Improvements {#improvements-6}

-   Support for `IF NOT EXISTS` in `ALTER TABLE ADD COLUMN` statements along with `IF EXISTS` in `DROP/MODIFY/CLEAR/COMMENT COLUMN`. [#3900](https://github.com/ClickHouse/ClickHouse/pull/3900) ([Boris Granveaud](https://github.com/bgranvea))
-   Function `parseDateTimeBestEffort`: support for formats `DD.MM.YYYY`, `DD.MM.YY`, `DD-MM-YYYY`, `DD-Mon-YYYY`, `DD/Month/YYYY` and similar. [#3922](https://github.com/ClickHouse/ClickHouse/pull/3922) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   `CapnProtoInputStream` now support jagged structures. [#4063](https://github.com/ClickHouse/ClickHouse/pull/4063) ([Odin Hultgren Van Der Horst](https://github.com/Miniwoffer))
-   Usability improvement: added a check that server process is started from the data directory’s owner. Do not allow to start server from root if the data belongs to non-root user. [#3785](https://github.com/ClickHouse/ClickHouse/pull/3785) ([sergey-v-galtsev](https://github.com/sergey-v-galtsev))
-   Better logic of checking required columns during analysis of queries with JOINs. [#3930](https://github.com/ClickHouse/ClickHouse/pull/3930) ([Artem Zuikov](https://github.com/4ertus2))
-   Decreased the number of connections in case of large number of Distributed tables in a single server. [#3726](https://github.com/ClickHouse/ClickHouse/pull/3726) ([Winter Zhang](https://github.com/zhang2014))
-   Supported totals row for `WITH TOTALS` query for ODBC driver. [#3836](https://github.com/ClickHouse/ClickHouse/pull/3836) ([Maksim Koritckiy](https://github.com/nightweb))
-   Allowed to use `Enum`s as integers inside if function. [#3875](https://github.com/ClickHouse/ClickHouse/pull/3875) ([Ivan](https://github.com/abyss7))
-   Added `low_cardinality_allow_in_native_format` setting. If disabled, do not use `LowCadrinality` type in `Native` format. [#3879](https://github.com/ClickHouse/ClickHouse/pull/3879) ([KochetovNicolai](https://github.com/KochetovNicolai))
-   Removed some redundant objects from compiled expressions cache to lower memory usage. [#4042](https://github.com/ClickHouse/ClickHouse/pull/4042) ([alesapin](https://github.com/alesapin))
-   Add check that `SET send_logs_level = 'value'` query accept appropriate value. [#3873](https://github.com/ClickHouse/ClickHouse/pull/3873) ([Sabyanin Maxim](https://github.com/s-mx))
-   Fixed data type check in type conversion functions. [#3896](https://github.com/ClickHouse/ClickHouse/pull/3896) ([Winter Zhang](https://github.com/zhang2014))

#### Performance Improvements {#performance-improvements-5}

-   Add a MergeTree setting `use_minimalistic_part_header_in_zookeeper`. If enabled, Replicated tables will store compact part metadata in a single part znode. This can dramatically reduce ZooKeeper snapshot size (especially if the tables have a lot of columns). Note that after enabling this setting you will not be able to downgrade to a version that does not support it. [#3960](https://github.com/ClickHouse/ClickHouse/pull/3960) ([Alex Zatelepin](https://github.com/ztlpn))
-   Add an DFA-based implementation for functions `sequenceMatch` and `sequenceCount` in case pattern does not contain time. [#4004](https://github.com/ClickHouse/ClickHouse/pull/4004) ([Léo Ercolanelli](https://github.com/ercolanelli-leo))
-   Performance improvement for integer numbers serialization. [#3968](https://github.com/ClickHouse/ClickHouse/pull/3968) ([Amos Bird](https://github.com/amosbird))
-   Zero left padding PODArray so that -1 element is always valid and zeroed. It’s used for branchless calculation of offsets. [#3920](https://github.com/ClickHouse/ClickHouse/pull/3920) ([Amos Bird](https://github.com/amosbird))
-   Reverted `jemalloc` version which lead to performance degradation. [#4018](https://github.com/ClickHouse/ClickHouse/pull/4018) ([alexey-milovidov](https://github.com/alexey-milovidov))

#### Backward Incompatible Changes {#backward-incompatible-changes-2}

-   Removed undocumented feature `ALTER MODIFY PRIMARY KEY` because it was superseded by the `ALTER MODIFY ORDER BY` command. [#3887](https://github.com/ClickHouse/ClickHouse/pull/3887) ([Alex Zatelepin](https://github.com/ztlpn))
-   Removed function `shardByHash`. [#3833](https://github.com/ClickHouse/ClickHouse/pull/3833) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Forbid using scalar subqueries with result of type `AggregateFunction`. [#3865](https://github.com/ClickHouse/ClickHouse/pull/3865) ([Ivan](https://github.com/abyss7))

#### Build/Testing/Packaging Improvements {#buildtestingpackaging-improvements-6}

-   Added support for PowerPC (`ppc64le`) build. [#4132](https://github.com/ClickHouse/ClickHouse/pull/4132) ([Danila Kutenin](https://github.com/danlark1))
-   Stateful functional tests are run on public available dataset. [#3969](https://github.com/ClickHouse/ClickHouse/pull/3969) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed error when the server cannot start with the `bash: /usr/bin/clickhouse-extract-from-config: Operation not permitted` message within Docker or systemd-nspawn. [#4136](https://github.com/ClickHouse/ClickHouse/pull/4136) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Updated `rdkafka` library to v1.0.0-RC5. Used cppkafka instead of raw C interface. [#4025](https://github.com/ClickHouse/ClickHouse/pull/4025) ([Ivan](https://github.com/abyss7))
-   Updated `mariadb-client` library. Fixed one of issues found by UBSan. [#3924](https://github.com/ClickHouse/ClickHouse/pull/3924) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Some fixes for UBSan builds. [#3926](https://github.com/ClickHouse/ClickHouse/pull/3926) [#3021](https://github.com/ClickHouse/ClickHouse/pull/3021) [#3948](https://github.com/ClickHouse/ClickHouse/pull/3948) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added per-commit runs of tests with UBSan build.
-   Added per-commit runs of PVS-Studio static analyzer.
-   Fixed bugs found by PVS-Studio. [#4013](https://github.com/ClickHouse/ClickHouse/pull/4013) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed glibc compatibility issues. [#4100](https://github.com/ClickHouse/ClickHouse/pull/4100) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Move Docker images to 18.10 and add compatibility file for glibc \>= 2.28 [#3965](https://github.com/ClickHouse/ClickHouse/pull/3965) ([alesapin](https://github.com/alesapin))
-   Add env variable if user do not want to chown directories in server Docker image. [#3967](https://github.com/ClickHouse/ClickHouse/pull/3967) ([alesapin](https://github.com/alesapin))
-   Enabled most of the warnings from `-Weverything` in clang. Enabled `-Wpedantic`. [#3986](https://github.com/ClickHouse/ClickHouse/pull/3986) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Added a few more warnings that are available only in clang 8. [#3993](https://github.com/ClickHouse/ClickHouse/pull/3993) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Link to `libLLVM` rather than to individual LLVM libs when using shared linking. [#3989](https://github.com/ClickHouse/ClickHouse/pull/3989) ([Orivej Desh](https://github.com/orivej))
-   Added sanitizer variables for test images. [#4072](https://github.com/ClickHouse/ClickHouse/pull/4072) ([alesapin](https://github.com/alesapin))
-   `clickhouse-server` debian package will recommend `libcap2-bin` package to use `setcap` tool for setting capabilities. This is optional. [#4093](https://github.com/ClickHouse/ClickHouse/pull/4093) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Improved compilation time, fixed includes. [#3898](https://github.com/ClickHouse/ClickHouse/pull/3898) ([proller](https://github.com/proller))
-   Added performance tests for hash functions. [#3918](https://github.com/ClickHouse/ClickHouse/pull/3918) ([filimonov](https://github.com/filimonov))
-   Fixed cyclic library dependences. [#3958](https://github.com/ClickHouse/ClickHouse/pull/3958) ([proller](https://github.com/proller))
-   Improved compilation with low available memory. [#4030](https://github.com/ClickHouse/ClickHouse/pull/4030) ([proller](https://github.com/proller))
-   Added test script to reproduce performance degradation in `jemalloc`. [#4036](https://github.com/ClickHouse/ClickHouse/pull/4036) ([alexey-milovidov](https://github.com/alexey-milovidov))
-   Fixed misspells in comments and string literals under `dbms`. [#4122](https://github.com/ClickHouse/ClickHouse/pull/4122) ([maiha](https://github.com/maiha))
-   Fixed typos in comments. [#4089](https://github.com/ClickHouse/ClickHouse/pull/4089) ([Evgenii Pravda](https://github.com/kvinty))

## [Changelog for 2018](../../whats-new/changelog/2018.md#clickhouse-release-18-16) {#changelog-for-2018}