2019 Changelog

## ClickHouse Release 19.10[​](#clickhouse-release-19-10 "Direct link to ClickHouse Release 19.10")

### ClickHouse Release 19.10.1.5, 2019-07-12[​](#clickhouse-release-19-10-1-5-2019-07-12 "Direct link to ClickHouse Release 19.10.1.5, 2019-07-12")

#### New Feature[​](#new-feature-7 "Direct link to New Feature")

- 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 "Direct link to Bug Fix")

- 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 "Direct link to Improvement")

- 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 "Direct link to Performance Improvement")

- 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 "Direct link to Build/Testing/Packaging Improvement")

- 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 "Direct link to ClickHouse Release 19.9")

### ClickHouse Release 19.9.3.31, 2019-07-05[​](#clickhouse-release-19-9-3-31-2019-07-05 "Direct link to ClickHouse Release 19.9.3.31, 2019-07-05")

#### Bug Fix[​](#bug-fix-23 "Direct link to Bug Fix")