ClickHouse/docs/changelogs/v21.2.2.8-stable.md

ClickHouse release v21.2.2.8-stable FIXME as compared to v21.1.1.5646-prestable

Backward Incompatible Change

• • Fix memory tracking for OPTIMIZE TABLE/merges - Account query memory limits and sampling for OPTIMIZE TABLE/merges. #18772 (Azat Khuzhin).
• Forbid lcm/gcd for floats. #19532 (Azat Khuzhin).
• Bitwise functions (bitAnd, bitOr, etc) are forbidden for floating point arguments. Now you have to do explicit cast to integer. #19853 (Azat Khuzhin).

New Feature

• add support for zstd long option for better compression of string columns to save space. #17184 (ygrek).
• • Added support of mapping LDAP group names, and attribute values in general, to local roles for users from ldap user directories. #17211 (Denis Glazachev).
• Data type Nested now supports arbitrary levels of nesting. Introduced subcolumns of complex types, such as size0 in Array, null in Nullable, names of Tuple elements, which can be read without reading of whole column. #17310 (Anton Popov).
• Add support of tuple argument to argMin and argMax functions. #17359 (Ildus Kurbangaliev).
• Added Nullable support for FlatDictionary, HashedDictionary, ComplexKeyHashedDictionary, DirectDictionary, ComplexKeyDirectDictionary, RangeHashedDictionary. #18236 (Maksim Kita).
• Disallow floating point column as partition key related to : #18421#event-4147046255. #18464 (hexiaoting).
• Add function decodeXMLComponent to decode characters for XML. SELECT decodeXMLComponent('Hello,"world"!'); #17659. #18542 (nauta).
• Added PostgreSQL table engine (both select/insert, with support for multidimensional arrays), also as table function. Added PostgreSQL dictionary source. Added PostgreSQL database engine. #18554 (Kseniia Sumarokova).
• Add SELECT ALL syntax. closes #18706. #18723 (flynn).
• Add three functions for map data type: 1. mapContains(map, key) to check weather map.keys include the second parameter key. 2. mapKeys(map) return all the keys in Array format 3. mapValues(map) return all the values in Array format. #18788 (hexiaoting).
• Support MetaKey+Enter hotkey binding in play ui. #19012 (sundyli).
• Function formatDateTime support the %Q modification to format date to quarter. ... #19224 (Jianmei Zhang).
• ... #19261 (RegulusZ).
• Add factories' objects names, created during query, into system.query_log. Closes #18495. #19371 (Kseniia Sumarokova).
• Add sign math function. #19527 (flynn).
• Added functions parseDateTimeBestEffortUSOrZero, parseDateTimeBestEffortUSOrNull. #19712 (Maksim Kita).
• ... #19764 (emhlbmc).

Performance Improvement

• Use a connection pool for S3 connections, controlled by the s3_max_connections settings. #13405 (Vladimir Chebotarev).
• Rewrite sumIf() and sum(if()) function to countIf() function when logically equivalent. #17041 (flynn).
• Update libcxx and use unstable ABI to provide better performance. #18914 (Daniel Kutenin).
• Faster parts removal by lowering the number of stat syscalls. This returns the optimization that existed while ago. More safe interface of IDisk. This closes #19065. #19086 (Alexey Milovidov).
• Speed up aggregate function sum. Improvement only visible on synthetic benchmarks and not very practical. #19216 (Alexey Milovidov).
• Support splitting Filter step of query plan into Expression + Filter pair. Together with Expression + Expression merging optimization (#17458) it may delay execution for some expressions after Filter step. #19253 (Nikolai Kochetov).
• Reduce lock contention for multiple layers of the Buffer engine. #19379 (Azat Khuzhin).
• Slightly improve server latency by removing access to configuration on every connection. #19863 (Alexey Milovidov).

Improvement

• Added support for WITH ... [AND] [PERIODIC] REFRESH [interval_in_sec] clause when creating LIVE VIEW tables. #14822 (vzakaznikov).
• • Add optimize_alias_column_prediction (on by default), that will: * Respect aliased columns in WHERE during partition pruning and skipping data using secondary indexes * Respect aliased columns in WHERE for trivial count queries for optimize_trivial_count * Respect aliased columns in GROUP BY/ORDER BY for optimize_aggregation_in_order/optimize_read_in_order. #16995 (sundyli).
• Updated AWS C++ SDK in order to utilize global regions in S3. #17870 (Vladimir Chebotarev).
• Support insert into table function cluster, and for both table functions remote and cluster, support distributing data across nodes by specify sharding key. Close #16752. #18264 (flynn).
• Support EXISTS VIEW syntax. #18552 (Du Chuan).
• Update librdkafka to v1.6.0-RC2. Fixes #18668. #18671 (filimonov).
• Allow CTE to be further aliased. Propagate CSE to subqueries in the same level when enable_global_with_statement = 1. This fixes #17378 . This fixes https://github.com/ClickHouse/ClickHouse/pull/16575#issuecomment-753416235 . #18684 (Amos Bird).
• Add [UInt8, UInt16, UInt32, UInt64] arguments types support for bitmapTransform, bitmapSubsetInRange, bitmapSubsetLimit, bitmapContains functions. This closes #18713. #18791 (sundyli).
• Added prefix-based S3 endpoint settings. #18812 (Vladimir Chebotarev).
• Fix issues with RIGHT and FULL JOIN of tables with aggregate function states. In previous versions exception about cloneResized method was thrown. #18818 (templarzq).
• • Check per-block checksum of the distributed batch on the sender before sending (without reading the file twice, the checksums will be verified while reading), this will avoid stuck of the INSERT on the receiver (on truncated .bin file on the sender) - Avoid reading .bin files twice for batched INSERT (it was required to calculate rows/bytes to take squashing into account, now this information included into the header, backward compatible is preserved). #18853 (Azat Khuzhin).
• Add normalizeQueryKeepNames and normalizedQueryHashKeepNames to normalize queries without masking long names with ?. This helps better analyze complex query logs. #18910 (Amos Bird).
• Docker image: several improvements for clickhouse-server entrypoint. #18954 (filimonov).
• Fixed PeekableReadBuffer: Memory limit exceed error when inserting data with huge strings. Fixes #18690. #18979 (Alexander Tokmakov).
• Explicitly set uid / gid of clickhouse user & group to the fixed values (101) in clickhouse-server images. #19096 (filimonov).
• The exception when function bar is called with certain NaN argument may be slightly misleading in previous versions. This fixes #19088. #19107 (Alexey Milovidov).
• Allow change max_server_memory_usage without restart. This closes #18154. #19186 (Alexey Milovidov).
• Fix wrong alignment of values of IPv4 data type in Pretty formats. They were aligned to the right, not to the left. This closes #19184. #19339 (Alexey Milovidov).
• Allow docker to be executed with arbitrary uid. #19374 (filimonov).
• Add metrics for MergeTree parts (Wide/Compact/InMemory) types. #19381 (Azat Khuzhin).
• Improve MySQL compatibility. #19387 (Daniil Kondratyev).
• Add http_referer field to system.query_log, system.processes, etc. This closes #19389. #19390 (Alexey Milovidov).
• toIPv6 function parses IPv4 addresses. #19518 (Bharat Nallan).
• Support using the new location of .debug file. This fixes #19348. #19520 (Amos Bird).
• Enable function length/empty/notEmpty for datatype map, which returns keys number in map. #19530 (李扬).
• Support constant result in function multiIf. #19533 (Maksim Kita).
• Add an option to disable validation of checksums on reading. Should never be used in production. Please do not expect any benefits in disabling it. It may only be used for experiments and benchmarks. The setting only applicable for tables of MergeTree family. Checksums are always validated for other table engines and when receiving data over network. In my observations there is no performance difference or it is less than 0.5%. #19588 (Alexey Milovidov).
• Dictionary better error message during attribute parsing. #19678 (Maksim Kita).
• Fix rare max_number_of_merges_with_ttl_in_pool limit overrun (more merges with TTL can be assigned) for non-replicated MergeTree. #19708 (alesapin).
• Insuffiient arguments check in positionCaseInsensitiveUTF8 function triggered address sanitizer. #19720 (Alexey Milovidov).
• Add separate pool for message brokers (RabbitMQ and Kafka). #19722 (Azat Khuzhin).
• In distributed queries if the setting async_socket_for_remote is enabled, it was possible to get stack overflow at least in debug build configuration if very deeply nested data type is used in table (e.g. Array(Array(Array(...more...)))). This fixes #19108. This change introduces minor backward incompatibility: excessive parenthesis in type definitions no longer supported, example: Array((UInt8)). #19736 (Alexey Milovidov).
• Table function S3 will use global region if the region can't be determined exactly. This closes #10998. #19750 (Vladimir Chebotarev).
• Clickhouse client query param CTE added test. #19762 (Maksim Kita).
• Correctly output infinite arguments for formatReadableTimeDelta function. In previous versions, there was implicit conversion to implementation specific integer value. #19791 (Alexey Milovidov).
• S3 table function now supports auto compression mode (autodetect). This closes #18754. #19793 (Vladimir Chebotarev).
• Set charset to utf8mb4 when interacting with remote MySQL servers. Fixes #19795. #19800 (Alexey Milovidov).
• Add --reconnect option to clickhouse-benchmark. When this option is specified, it will reconnect before every request. This is needed for testing. #19872 (Alexey Milovidov).

Bug Fix

• fix data type convert issue for mysql engine ... #18124 (bo zeng).
• SELECT count() FROM table now can be executed if only one any column can be selected from the table. This PR fixes #10639. #18233 (Vitaly Baranov).
• Fix index analysis of binary functions with constant argument which leads to wrong query results. This fixes #18364. #18373 (Amos Bird).
• Disable constant folding for subqueries on the analysis stage, when the result cannot be calculated. #18446 (Azat Khuzhin).
• Attach partition should reset the mutation. #18804. #18935 (fastio).
• Fix bug when mutation with some escaped text (like ALTER ... UPDATE e = CAST('foo', 'Enum8(\'foo\' = 1') serialized incorrectly. Fixes #18878. #18944 (alesapin).
• Fix error Task was not found in task queue (possible only for remote queries, with async_socket_for_remote = 1). #18964 (Nikolai Kochetov).
• to fix #18894 Add a check to avoid exception when long column alias('table.column' style, usually auto-generated by BI tools like Looker) equals to long table name. #18968 (Daniel Qin).
• Fix incorrect behavior when ALTER TABLE ... DROP PART 'part_name' query removes all deduplication blocks for the whole partition. Fixes #18874. #18969 (alesapin).
• Fixed rare crashes when server run out of memory. #18976 (Alexander Tokmakov).
• Fixed very rare deadlock at shutdown. #18977 (Alexander Tokmakov).
• Fix possible exception QueryPipeline stream: different number of columns caused by merging of query plan's Expression steps. Fixes #18190. #18980 (Nikolai Kochetov).
• Disable optimize_move_functions_out_of_any because optimization is not always correct. This closes #18051. This closes #18973. #18981 (Alexey Milovidov).
• Join tries to materialize const columns, but our code waits for them in other places. #18982 (Nikita Mikhaylov).
• Fix inserting of LowCardinality column to table with TinyLog engine. Fixes #18629. #19010 (Nikolai Kochetov).
• Fix possible error Expected single dictionary argument for function if use function ignore with LowCardinality argument. Fixes #14275. #19016 (Nikolai Kochetov).
• Make sure groupUniqArray returns correct type for argument of Enum type. This closes #17875. #19019 (Alexey Milovidov).
• Restrict MODIFY TTL queries for MergeTree tables created in old syntax. Previously the query succeeded, but actually it had no effect. #19064 (Anton Popov).
• Fixed There is no checkpoint error when inserting data through http interface using Template or CustomSeparated format. Fixes #19021. #19072 (Alexander Tokmakov).
• Simplify the implementation of tupleHammingDistance. Support for tuples of any equal length. Fixes #19029. #19084 (Nikolai Kochetov).
• Fix startup bug when clickhouse was not able to read compression codec from LowCardinality(Nullable(...)) and throws exception Attempt to read after EOF. Fixes #18340. #19101 (alesapin).
• Fix bug in merge tree data writer which can lead to marks with bigger size than fixed granularity size. Fixes #18913. #19123 (alesapin).
• Fix infinite reading from file in ORC format (was introduced in #10580). Fixes #19095. #19134 (Nikolai Kochetov).
• • Split RemoteQueryExecutorReadContext into module part - Fix leaking of pipe fd for async_socket_for_remote. #19153 (Azat Khuzhin).
• Fix bug when concurrent ALTER and DROP queries may hang while processing ReplicatedMergeTree table. #19237 (alesapin).
• Do not mark file for distributed send as broken on EOF. #19290 (Azat Khuzhin).
• Fix error Cannot convert column now64() because it is constant but values of constants are different in source and result. Continuation of #7156. #19316 (Nikolai Kochetov).
• Fixed possible wrong result or segfault on aggregation when Materialized View and its target table have different structure. Fixes #18063. #19322 (Alexander Tokmakov).
• Fix system.parts _state column (LOGICAL_ERROR when querying this column, due to incorrect order). #19346 (Azat Khuzhin).
• Added cast, accurateCast, accurateCastOrNull performance tests. #19354 (Maksim Kita).
• • Fix default value in join types with non-zero default (e.g. some Enums). Closes #18197. #19360 (Vladimir C).
• Fix possible buffer overflow in Uber H3 library. See https://github.com/uber/h3/issues/392. This closes #19219. #19383 (Alexey Milovidov).
• Uninitialized memory read was possible in encrypt/decrypt functions if empty string was passed as IV. This closes #19391. #19397 (Alexey Milovidov).
• Fix possible error Extremes transform was already added to pipeline. Fixes #14100. #19430 (Nikolai Kochetov).
• Fixed very rare bug that might cause mutation to hang after DROP/DETACH/REPLACE/MOVE PARTITION. It was partially fixed by #15537 for the most cases. #19443 (Alexander Tokmakov).
• Mark distributed batch as broken in case of empty data block in one of files. #19449 (Azat Khuzhin).
• Buffer overflow (on memory read) was possible if addMonth function was called with specifically crafted arguments. This fixes #19441. This fixes #19413. #19472 (Alexey Milovidov).
• Fix wrong deserialization of columns description. It makes INSERT into a table with a column named \ impossible. #19479 (Alexey Milovidov).
• Fix SIGSEGV with merge_tree_min_rows_for_concurrent_read/merge_tree_min_bytes_for_concurrent_read=0/UINT64_MAX. #19528 (Azat Khuzhin).
• Query CREATE DICTIONARY id expression fix. #19571 (Maksim Kita).
• DROP/DETACH TABLE table ON CLUSTER cluster SYNC query might hang, it's fixed. Fixes #19568. #19572 (Alexander Tokmakov).
• Fix use-after-free of the CompressedWriteBuffer in Connection after disconnect. #19599 (Azat Khuzhin).
• Fix wrong result of function neighbor for LowCardinality argument. Fixes #10333. #19617 (Nikolai Kochetov).
• Some functions with big integers may cause segfault. Big integers is experimental feature. This closes #19667. #19672 (Alexey Milovidov).
• Backported in #19986: Background thread which executes ON CLUSTER queries might hang waiting for dropped replicated table to do something. It's fixed. #19684 (yiguolei).
• Fix rare bug when some replicated operations (like mutation) cannot process some parts after data corruption. Fixes #19593. #19702 (alesapin).
• Fix a segmentation fault in bitmapAndnot function. Fixes #19668. #19713 (Maksim Kita).
• Fix crash when nested column name was used in WHERE or PREWHERE. Fixes #19755. #19763 (Nikolai Kochetov).
• Fixed stack overflow when using accurate comparison of arithmetic type with string type. #19773 (Alexander Tokmakov).
• In previous versions, unusual arguments for function arrayEnumerateUniq may cause crash or infinite loop. This closes #19787. #19788 (Alexey Milovidov).
• The function greatCircleAngle returned inaccurate results in previous versions. This closes #19769. #19789 (Alexey Milovidov).
• Backported in #19922: Fix clickhouse-client abort exception while executing only select. #19790 (李扬).
• Fix filtering by UInt8 greater than 127. #19799 (Anton Popov).
• Backported in #20007: Fix starting the server with tables having default expressions containing dictGet(). Allow getting return type of dictGet() without loading dictionary. #19805 (Vitaly Baranov).
• Fix crash when pushing down predicates to union distinct subquery. This fixes #19855. #19861 (Amos Bird).
• Fix argMin/argMax crash when combining with -If. This fixes https://clickhouse-test-reports.s3.yandex.net/19800/7b8589dbde5bc621d1bcfd68a713e4684183f593/fuzzer_ubsan/report.html#fail1. #19868 (Amos Bird).
• Backported in #19939: Deadlock was possible if system.text_log is enabled. This fixes #19874. #19875 (Alexey Milovidov).
• Backported in #19935: BloomFilter index crash fix. Fixes #19757. #19884 (Maksim Kita).
• Backported in #19996: - Fix a segfault in function fromModifiedJulianDay when the argument type is Nullable(T) for any integral types other than Int32. #19959 (PHO).
• Backported in #20112: EmbeddedRocksDB is an experimental storage. Fix the issue with lack of proper type checking. Simplified code. This closes #19967. #19972 (Alexey Milovidov).
• Backported in #20028: Prevent "Connection refused" in docker during initialization script execution. #20012 (filimonov).
• Backported in #20123: MaterializeMySQL: Fix replication for statements that update several tables. #20066 (Håvard Kvålen).
• Backported in #20146: Fix server crash after query with if function with Tuple type of then/else branches result. Tuple type must contain Array or another complex type. Fixes #18356. #20133 (alesapin).

Build/Testing/Packaging Improvement

• Restore Kafka input in FreeBSD builds. #18924 (Alexandre Snarskii).
• Add integration tests run with memory sanitizer. #18974 (alesapin).
• Add SQLancer test docker image to run check in CI. #19006 (Ilya Yatsishin).
• Added tests for defaults in URL and File engine. This closes #5666. #19015 (Nikita Mikhaylov).
• • Enabling RBAC tests - Tests for SYSTEM privileges - Requirements name changes. #19017 (MyroTk).
• Query Fuzzer will fuzz newly added tests more extensively. This closes #18916. #19185 (Alexey Milovidov).
• Allow building librdkafka without ssl. #19337 (filimonov).
• Avoid UBSan reports in arrayElement function, substring and arraySum. Fixes #19305. Fixes #19287. This closes #19336. #19347 (Alexey Milovidov).
• Fix potential nullptr dereference in table function VALUES. #19357 (Alexey Milovidov).
• Allow building ClickHouse with Kafka support on arm64. #19369 (filimonov).
• Integrate with Big List of Naughty Strings for better fuzzing. #19480 (Alexey Milovidov).
• Allow to explicitly enable or disable watchdog via environment variable CLICKHOUSE_WATCHDOG_ENABLE. By default it is enabled if server is not attached to terminal. #19522 (Alexey Milovidov).
• Updating TestFlows AES encryption tests to support changes to the encrypt plaintext parameter. #19674 (vzakaznikov).
• Made generation of macros.xml easier for integration tests. No more excessive logging from dicttoxml. dicttoxml project is not active for 5+ years. #19697 (Ilya Yatsishin).
• Remove --project-directory for docker-compose in integration test. Fix logs formatting from docker container. #19706 (Ilya Yatsishin).
• Fixed MemorySanitizer errors in cyrus-sasl and musl. #19821 (Ilya Yatsishin).
• Add test for throwing an exception on inserting incorrect data in CollapsingMergeTree. #19851 (Kruglov Pavel).
• Adding retries for docker-compose start, stop and restart in TestFlows tests. #19852 (vzakaznikov).

NO CL ENTRY

• NO CL ENTRY: 'Remove useless codes'. #19293 (sundyli).
• NO CL ENTRY: 'Merging #19387'. #19683 (Alexey Milovidov).