2023 Changelog

### ClickHouse release 23.4, 2023-04-26. [Presentation](https://presentations.clickhouse.com/2023-release-23.4/), [Video](https://www.youtube.com/watch?v=4rrf6bk_mOg)[​](#234 "Direct link to 234")

#### Backward Incompatible Change[​](#backward-incompatible-change-7 "Direct link to Backward Incompatible Change")

- Formatter '%M' in function formatDateTime() now prints the month name instead of the minutes. This makes the behavior consistent with MySQL. The previous behavior can be restored using setting "formatdatetime\_parsedatetime\_m\_is\_month\_name = 0". [#47246](https://github.com/ClickHouse/ClickHouse/pull/47246) ([Robert Schulze](https://github.com/rschu1ze)).
- This change makes sense only if you are using the virtual filesystem cache. If `path` in the virtual filesystem cache configuration is not empty and is not an absolute path, then it will be put in `<clickhouse server data directory>/caches/<path_from_cache_config>`. [#48784](https://github.com/ClickHouse/ClickHouse/pull/48784) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Primary/secondary indices and sorting keys with identical expressions are now rejected. This behavior can be disabled using setting `allow_suspicious_indices`. [#48536](https://github.com/ClickHouse/ClickHouse/pull/48536) ([凌涛](https://github.com/lingtaolf)).

#### New Feature[​](#new-feature-8 "Direct link to New Feature")

- Support new aggregate function `quantileGK`/`quantilesGK`, like [approx\_percentile](https://spark.apache.org/docs/latest/api/sql/index.html#approx_percentile) in spark. Greenwald-Khanna algorithm refer to <http://infolab.stanford.edu/~datar/courses/cs361a/papers/quantiles.pdf>. [#46428](https://github.com/ClickHouse/ClickHouse/pull/46428) ([李扬](https://github.com/taiyang-li)).
- Add a statement `SHOW COLUMNS` which shows distilled information from system.columns. [#48017](https://github.com/ClickHouse/ClickHouse/pull/48017) ([Robert Schulze](https://github.com/rschu1ze)).
- Added `LIGHTWEIGHT` and `PULL` modifiers for `SYSTEM SYNC REPLICA` query. `LIGHTWEIGHT` version waits for fetches and drop-ranges only (merges and mutations are ignored). `PULL` version pulls new entries from ZooKeeper and does not wait for them. Fixes [#47794](https://github.com/ClickHouse/ClickHouse/issues/47794). [#48085](https://github.com/ClickHouse/ClickHouse/pull/48085) ([Alexander Tokmakov](https://github.com/tavplubix)).
- Add `kafkaMurmurHash` function for compatibility with Kafka DefaultPartitioner. Closes [#47834](https://github.com/ClickHouse/ClickHouse/issues/47834). [#48185](https://github.com/ClickHouse/ClickHouse/pull/48185) ([Nikolay Degterinsky](https://github.com/evillique)).
- Allow to easily create a user with the same grants as the current user by using `GRANT CURRENT GRANTS`. [#48262](https://github.com/ClickHouse/ClickHouse/pull/48262) ([pufit](https://github.com/pufit)).
- Add statistical aggregate function `kolmogorovSmirnovTest`. Close [#48228](https://github.com/ClickHouse/ClickHouse/issues/48228). [#48325](https://github.com/ClickHouse/ClickHouse/pull/48325) ([FFFFFFFHHHHHHH](https://github.com/FFFFFFFHHHHHHH)).
- Added a `lost_part_count` column to the `system.replicas` table. The column value shows the total number of lost parts in the corresponding table. Value is stored in zookeeper and can be used instead of not persistent `ReplicatedDataLoss` profile event for monitoring. [#48526](https://github.com/ClickHouse/ClickHouse/pull/48526) ([Sergei Trifonov](https://github.com/serxa)).
- Add `soundex` function for compatibility. Closes [#39880](https://github.com/ClickHouse/ClickHouse/issues/39880). [#48567](https://github.com/ClickHouse/ClickHouse/pull/48567) ([FriendLey](https://github.com/FriendLey)).
- Support `Map` type for JSONExtract. [#48629](https://github.com/ClickHouse/ClickHouse/pull/48629) ([李扬](https://github.com/taiyang-li)).
- Add `PrettyJSONEachRow` format to output pretty JSON with new line delimiters and 4 space indents. [#48898](https://github.com/ClickHouse/ClickHouse/pull/48898) ([Kruglov Pavel](https://github.com/Avogar)).
- Add `ParquetMetadata` input format to read Parquet file metadata. [#48911](https://github.com/ClickHouse/ClickHouse/pull/48911) ([Kruglov Pavel](https://github.com/Avogar)).
- Add `extractKeyValuePairs` function to extract key value pairs from strings. Input strings might contain noise (i.e. log files / do not need to be 100% formatted in key-value-pair format), the algorithm will look for key value pairs matching the arguments passed to the function. As of now, function accepts the following arguments: `data_column` (mandatory), `key_value_pair_delimiter` (defaults to `:`), `pair_delimiters` (defaults to `\space \, \;`) and `quoting_character` (defaults to double quotes). [#43606](https://github.com/ClickHouse/ClickHouse/pull/43606) ([Arthur Passos](https://github.com/arthurpassos)).
- Functions replaceOne(), replaceAll(), replaceRegexpOne() and replaceRegexpAll() can now be called with non-const pattern and replacement arguments. [#46589](https://github.com/ClickHouse/ClickHouse/pull/46589) ([Robert Schulze](https://github.com/rschu1ze)).
- Added functions to work with columns of type `Map`: `mapConcat`, `mapSort`, `mapExists`. [#48071](https://github.com/ClickHouse/ClickHouse/pull/48071) ([Anton Popov](https://github.com/CurtizJ)).

#### Performance Improvement[​](#performance-improvement-8 "Direct link to Performance Improvement")