- Fixed bug with possible race condition in replication that could lead to data loss. This issue affects versions 1.1.54310 and 1.1.54318. If you use one of these versions with Replicated tables, the update is strongly recommended. This issue shows in logs in Warning messages like `Part ... from own log doesn't exist.` The issue is relevant even if you don’t see these messages in logs.
- Added support for loading [CatBoost](https://catboost.yandex/) models and applying them to data stored in ClickHouse.
- Added support for time zones with non-integer offsets from UTC.
- Added support for arithmetic operations with time intervals.
- The range of values for the Date and DateTime types is extended to the year 2105.
- Added the `CREATE MATERIALIZED VIEW x TO y` query (specifies an existing table for storing the data of a materialized view).
- Added the `ATTACH TABLE` query without arguments.
- The processing logic for Nested columns with names ending in -Map in a SummingMergeTree table was extracted to the sumMap aggregate function. You can now specify such columns explicitly.
- Max size of the IP trie dictionary is increased to 128M entries.
- Added the getSizeOfEnumType function.
- Added the sumWithOverflow aggregate function.
- Added support for the Cap’n Proto input format.
- You can now customize compression level when using the zstd algorithm.
- Fixed hangups when synchronously inserting into a Distributed table.
- Fixed nonatomic adding and removing of parts in Replicated tables.
- Data inserted into a materialized view is not subjected to unnecessary deduplication.
- Executing a query to a Distributed table for which the local replica is lagging and remote replicas are unavailable does not result in an error anymore.
- Users don’t need access permissions to the `default` database to create temporary tables anymore.
- Fixed crashing when specifying the Array type without arguments.
- Fixed hangups when the disk volume containing server logs is full.
- Fixed an overflow in the toRelativeWeekNum function for the first week of the Unix epoch.
- Added the `pointInPolygon` function for working with coordinates on a coordinate plane.
- Added the `sumMap` aggregate function for calculating the sum of arrays, similar to `SummingMergeTree`.
- Added the `trunc` function. Improved performance of the rounding functions (`round`, `floor`, `ceil`, `roundToExp2`) and corrected the logic of how they work. Changed the logic of the `roundToExp2` function for fractions and negative numbers.
- The ClickHouse executable file is now less dependent on the libc version. The same ClickHouse executable file can run on a wide variety of Linux systems. There is still a dependency when using compiled queries (with the setting `compile = 1` , which is not used by default).
- Reduced the time needed for dynamic compilation of queries.
-`SYSTEM` queries for server administration: `SYSTEM RELOAD DICTIONARY`, `SYSTEM RELOAD DICTIONARIES`, `SYSTEM DROP DNS CACHE`, `SYSTEM SHUTDOWN`, `SYSTEM KILL`.
- Added functions for working with arrays: `concat`, `arraySlice`, `arrayPushBack`, `arrayPushFront`, `arrayPopBack`, `arrayPopFront`.
- Added `root` and `identity` parameters for the ZooKeeper configuration. This allows you to isolate individual users on the same ZooKeeper cluster.
- Added aggregate functions `groupBitAnd`, `groupBitOr`, and `groupBitXor` (for compatibility, they are also available under the names `BIT_AND`, `BIT_OR`, and `BIT_XOR`).
- External dictionaries can be loaded from MySQL by specifying a socket in the filesystem.
- External dictionaries can be loaded from MySQL over SSL (`ssl_cert`, `ssl_key`, `ssl_ca` parameters).
- Added the `max_network_bandwidth_for_user` setting to restrict the overall bandwidth use for queries per user.
- Support for `DROP TABLE` for temporary tables.
- Support for reading `DateTime` values in Unix timestamp format from the `CSV` and `JSONEachRow` formats.
- Lagging replicas in distributed queries are now excluded by default (the default threshold is 5 minutes).
- FIFO locking is used during ALTER: an ALTER query isn’t blocked indefinitely for continuously running queries.
- Option to set `umask` in the config file.
- Improved performance for queries with `DISTINCT` .
- Improved the process for deleting old nodes in ZooKeeper. Previously, old nodes sometimes didn’t get deleted if there were very frequent inserts, which caused the server to be slow to shut down, among other things.
- Fixed randomization when choosing hosts for the connection to ZooKeeper.
- Fixed the exclusion of lagging replicas in distributed queries if the replica is localhost.
- Fixed an error where a data part in a `ReplicatedMergeTree` table could be broken after running `ALTER MODIFY` on an element in a `Nested` structure.
- Fixed an error that could cause SELECT queries to “hang”.
- Improvements to distributed DDL queries.
- Fixed the query `CREATE TABLE ... AS <materialized view>`.
- Resolved the deadlock in the `ALTER ... CLEAR COLUMN IN PARTITION` query for `Buffer` tables.
- Fixed the invalid default value for `Enum` s (0 instead of the minimum) when using the `JSONEachRow` and `TSKV` formats.
- Resolved the appearance of zombie processes when using a dictionary with an `executable` source.
- There is now a higher default value for the MergeTree setting `max_bytes_to_merge_at_max_space_in_pool` (the maximum total size of data parts to merge, in bytes): it has increased from 100 GiB to 150 GiB. This might result in large merges running after the server upgrade, which could cause an increased load on the disk subsystem. If the free space available on the server is less than twice the total amount of the merges that are running, this will cause all other merges to stop running, including merges of small data parts. As a result, INSERT queries will fail with the message “Merges are processing significantly slower than inserts.” Use the `SELECT * FROM system.merges` query to monitor the situation. You can also check the `DiskSpaceReservedForMerge` metric in the `system.metrics` table, or in Graphite. You don’t need to do anything to fix this, since the issue will resolve itself once the large merges finish. If you find this unacceptable, you can restore the previous value for the `max_bytes_to_merge_at_max_space_in_pool` setting. To do this, go to the `<merge_tree>` section in config.xml, set ``` <merge_tree>``<max_bytes_to_merge_at_max_space_in_pool>107374182400</max_bytes_to_merge_at_max_space_in_pool> ``` and restart the server.
- Added an optional WITH section for a SELECT query. Example query: `WITH 1+1 AS a SELECT a, a*a`
- INSERT can be performed synchronously in a Distributed table: OK is returned only after all the data is saved on all the shards. This is activated by the setting insert\_distributed\_sync=1.
- Added the UUID data type for working with 16-byte identifiers.
- Added aliases of CHAR, FLOAT and other types for compatibility with the Tableau.
- Added the functions toYYYYMM, toYYYYMMDD, and toYYYYMMDDhhmmss for converting time into numbers.
- You can use IP addresses (together with the hostname) to identify servers for clustered DDL queries.
- Added support for non-constant arguments and negative offsets in the function `substring(str, pos, len).`
- Added the max\_size parameter for the `groupArray(max_size)(column)` aggregate function, and optimized its performance.
- Improved error messages for queries with invalid syntax.
- Significantly reduced memory consumption and improved performance when merging large sections of MergeTree data.
- Significantly increased the performance of data merges for the ReplacingMergeTree engine.
- Improved performance for asynchronous inserts from a Distributed table by combining multiple source inserts. To enable this functionality, use the setting distributed\_directory\_monitor\_batch\_inserts=1.
- Added the `output_format_json_quote_denormals` setting, which enables outputting nan and inf values in JSON format.
- Optimized stream allocation when reading from a Distributed table.
- Settings can be configured in readonly mode if the value doesn’t change.
- Added the ability to retrieve non-integer granules of the MergeTree engine in order to meet restrictions on the block size specified in the preferred\_block\_size\_bytes setting. The purpose is to reduce the consumption of RAM and increase cache locality when processing queries from tables with large columns.
- Efficient use of indexes that contain expressions like `toStartOfHour(x)` for conditions like `toStartOfHour(x) op сonstexpr.`
- Added new settings for MergeTree engines (the merge\_tree section in config.xml):
- replicated\_deduplication\_window\_seconds sets the number of seconds allowed for deduplicating inserts in Replicated tables.
- cleanup\_delay\_period sets how often to start cleanup to remove outdated data.
- replicated\_can\_become\_leader can prevent a replica from becoming the leader (and assigning merges).
- Accelerated cleanup to remove outdated data from ZooKeeper.
- Multiple improvements and fixes for clustered DDL queries. Of particular interest is the new setting distributed\_ddl\_task\_timeout, which limits the time to wait for a response from the servers in the cluster. If a ddl request has not been performed on all hosts, a response will contain a timeout error and a request will be executed in an async mode.
- Improved display of stack traces in the server logs.
- Added the “none” value for the compression method.
- You can use multiple dictionaries\_config sections in config.xml.
- It is possible to connect to MySQL through a socket in the file system.
- The system.parts table has a new column with information about the size of marks, in bytes.
