2018 Changelog

### ClickHouse Release 18.10.3, 2018-08-13[​](#clickhouse-release-18-10-3-2018-08-13 "Direct link to ClickHouse Release 18.10.3, 2018-08-13")

#### New Features:[​](#new-features-5 "Direct link to New Features:")

- HTTPS can be used for replication. [#2760](https://github.com/ClickHouse/ClickHouse/pull/2760)
- Added the functions `murmurHash2_64`, `murmurHash3_32`, `murmurHash3_64`, and `murmurHash3_128` in addition to the existing `murmurHash2_32`. [#2791](https://github.com/ClickHouse/ClickHouse/pull/2791)
- Support for Nullable types in the ClickHouse ODBC driver (`ODBCDriver2` output format). [#2834](https://github.com/ClickHouse/ClickHouse/pull/2834)
- Support for `UUID` in the key columns.

#### Improvements:[​](#improvements-5 "Direct link to Improvements:")

- Clusters can be removed without restarting the server when they are deleted from the config files. [#2777](https://github.com/ClickHouse/ClickHouse/pull/2777)
- External dictionaries can be removed without restarting the server when they are removed from config files. [#2779](https://github.com/ClickHouse/ClickHouse/pull/2779)
- Added `SETTINGS` support for the `Kafka` table engine. [Alexander Marshalov](https://github.com/ClickHouse/ClickHouse/pull/2781)
- Improvements for the `UUID` data type (not yet complete). [#2618](https://github.com/ClickHouse/ClickHouse/pull/2618)
- Support for empty parts after merges in the `SummingMergeTree`, `CollapsingMergeTree` and `VersionedCollapsingMergeTree` engines. [#2815](https://github.com/ClickHouse/ClickHouse/pull/2815)
- Old records of completed mutations are deleted (`ALTER DELETE`). [#2784](https://github.com/ClickHouse/ClickHouse/pull/2784)
- Added the `system.merge_tree_settings` table. [Kirill Shvakov](https://github.com/ClickHouse/ClickHouse/pull/2841)
- The `system.tables` table now has dependency columns: `dependencies_database` and `dependencies_table`. [Winter Zhang](https://github.com/ClickHouse/ClickHouse/pull/2851)
- Added the `max_partition_size_to_drop` config option. [#2782](https://github.com/ClickHouse/ClickHouse/pull/2782)
- Added the `output_format_json_escape_forward_slashes` option. [Alexander Bocharov](https://github.com/ClickHouse/ClickHouse/pull/2812)
- Added the `max_fetch_partition_retries_count` setting. [#2831](https://github.com/ClickHouse/ClickHouse/pull/2831)
- Added the `prefer_localhost_replica` setting for disabling the preference for a local replica and going to a local replica without inter-process interaction. [#2832](https://github.com/ClickHouse/ClickHouse/pull/2832)
- The `quantileExact` aggregate function returns `nan` in the case of aggregation on an empty `Float32` or `Float64` set. [Sundy Li](https://github.com/ClickHouse/ClickHouse/pull/2855)

#### Bug Fixes:[​](#bug-fixes-14 "Direct link to Bug Fixes:")

- Removed unnecessary escaping of the connection string parameters for ODBC, which made it impossible to establish a connection. This error occurred in version 18.6.0.
- Fixed the logic for processing `REPLACE PARTITION` commands in the replication queue. If there are two `REPLACE` commands for the same partition, the incorrect logic could cause one of them to remain in the replication queue and not be executed. [#2814](https://github.com/ClickHouse/ClickHouse/pull/2814)
- Fixed a merge bug when all data parts were empty (parts that were formed from a merge or from `ALTER DELETE` if all data was deleted). This bug appeared in version 18.1.0. [#2930](https://github.com/ClickHouse/ClickHouse/pull/2930)
- Fixed an error for concurrent `Set` or `Join`. [Amos Bird](https://github.com/ClickHouse/ClickHouse/pull/2823)
- Fixed the `Block structure mismatch in UNION stream: different number of columns` error that occurred for `UNION ALL` queries inside a sub-query if one of the `SELECT` queries contains duplicate column names. [Winter Zhang](https://github.com/ClickHouse/ClickHouse/pull/2094)
- Fixed a memory leak if an exception occurred when connecting to a MySQL server.
- Fixed incorrect clickhouse-client response code in case of a query error.
- Fixed incorrect behavior of materialized views containing DISTINCT. [#2795](https://github.com/ClickHouse/ClickHouse/issues/2795)

#### Backward Incompatible Changes[​](#backward-incompatible-changes-4 "Direct link to Backward Incompatible Changes")

- Removed support for CHECK TABLE queries for Distributed tables.

#### Build Changes:[​](#build-changes-3 "Direct link to Build Changes:")

- The allocator has been replaced: `jemalloc` is now used instead of `tcmalloc`. In some scenarios, this increases speed up to 20%. However, there are queries that have slowed by up to 20%. Memory consumption has been reduced by approximately 10% in some scenarios, with improved stability. With highly competitive loads, CPU usage in userspace and in system shows just a slight increase. [#2773](https://github.com/ClickHouse/ClickHouse/pull/2773)
- Use of libressl from a submodule. [#1983](https://github.com/ClickHouse/ClickHouse/pull/1983) [#2807](https://github.com/ClickHouse/ClickHouse/pull/2807)
- Use of unixodbc from a submodule. [#2789](https://github.com/ClickHouse/ClickHouse/pull/2789)
- Use of mariadb-connector-c from a submodule. [#2785](https://github.com/ClickHouse/ClickHouse/pull/2785)
- Added functional test files to the repository that depend on the availability of test data (for the time being, without the test data itself).

## ClickHouse Release 18.6[​](#clickhouse-release-18-6 "Direct link to ClickHouse Release 18.6")

### ClickHouse Release 18.6.0, 2018-08-02[​](#clickhouse-release-18-6-0-2018-08-02 "Direct link to ClickHouse Release 18.6.0, 2018-08-02")

#### New Features:[​](#new-features-6 "Direct link to New Features:")

- Added support for ON expressions for the JOIN ON syntax:
  `JOIN ON Expr([table.]column ...) = Expr([table.]column, ...) [AND Expr([table.]column, ...) = Expr([table.]column, ...) ...]`
  The expression must be a chain of equalities joined by the AND operator. Each side of the equality can be an arbitrary expression over the columns of one of the tables. The use of fully qualified column names is supported (`table.name`, `database.table.name`, `table_alias.name`, `subquery_alias.name`) for the right table. [#2742](https://github.com/ClickHouse/ClickHouse/pull/2742)
- HTTPS can be enabled for replication. [#2760](https://github.com/ClickHouse/ClickHouse/pull/2760)

#### Improvements:[​](#improvements-6 "Direct link to Improvements:")

- The server passes the patch component of its version to the client. Data about the patch version component is in `system.processes` and `query_log`. [#2646](https://github.com/ClickHouse/ClickHouse/pull/2646)

## ClickHouse Release 18.5[​](#clickhouse-release-18-5 "Direct link to ClickHouse Release 18.5")

### ClickHouse Release 18.5.1, 2018-07-31[​](#clickhouse-release-18-5-1-2018-07-31 "Direct link to ClickHouse Release 18.5.1, 2018-07-31")

#### New Features:[​](#new-features-7 "Direct link to New Features:")

- Added the hash function `murmurHash2_32` [#2756](https://github.com/ClickHouse/ClickHouse/pull/2756).

#### Improvements:[​](#improvements-7 "Direct link to Improvements:")

- Now you can use the `from_env` [#2741](https://github.com/ClickHouse/ClickHouse/pull/2741) attribute to set values in config files from environment variables.
- Added case-insensitive versions of the `coalesce`, `ifNull`, and `nullIf functions` [#2752](https://github.com/ClickHouse/ClickHouse/pull/2752).

#### Bug Fixes:[​](#bug-fixes-15 "Direct link to Bug Fixes:")

- Fixed a possible bug when starting a replica [#2759](https://github.com/ClickHouse/ClickHouse/pull/2759).

## ClickHouse Release 18.4[​](#clickhouse-release-18-4 "Direct link to ClickHouse Release 18.4")

### ClickHouse Release 18.4.0, 2018-07-28[​](#clickhouse-release-18-4-0-2018-07-28 "Direct link to ClickHouse Release 18.4.0, 2018-07-28")

#### New Features:[​](#new-features-8 "Direct link to New Features:")