2020 Changelog

- Proper error handling during insert into MergeTree with S3. MergeTree over S3 is an experimental feature. [#15657](https://github.com/ClickHouse/ClickHouse/pull/15657) ([Pavel Kovalenko](https://github.com/Jokser)).
- Fixed bug with S3 table function: region from URL was not applied to S3 client configuration. [#15646](https://github.com/ClickHouse/ClickHouse/pull/15646) ([Vladimir Chebotarev](https://github.com/excitoon)).
- Fix the order of destruction for resources in `ReadFromStorage` step of query plan. It might cause crashes in rare cases. Possibly connected with [#15610](https://github.com/ClickHouse/ClickHouse/issues/15610). [#15645](https://github.com/ClickHouse/ClickHouse/pull/15645) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Subtract `ReadonlyReplica` metric when detach readonly tables. [#15592](https://github.com/ClickHouse/ClickHouse/pull/15592) ([sundyli](https://github.com/sundy-li)).
- Fixed `Element ... is not a constant expression` error when using `JSON*` function result in `VALUES`, `LIMIT` or right side of `IN` operator. [#15589](https://github.com/ClickHouse/ClickHouse/pull/15589) ([tavplubix](https://github.com/tavplubix)).
- Query will finish faster in case of exception. Cancel execution on remote replicas if exception happens. [#15578](https://github.com/ClickHouse/ClickHouse/pull/15578) ([Azat Khuzhin](https://github.com/azat)).
- Prevent the possibility of error message `Could not calculate available disk space (statvfs), errno: 4, strerror: Interrupted system call`. This fixes [#15541](https://github.com/ClickHouse/ClickHouse/issues/15541). [#15557](https://github.com/ClickHouse/ClickHouse/pull/15557) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix `Database <db> does not exist.` in queries with IN and Distributed table when there's no database on initiator. [#15538](https://github.com/ClickHouse/ClickHouse/pull/15538) ([Artem Zuikov](https://github.com/4ertus2)).
- Mutation might hang waiting for some non-existent part after `MOVE` or `REPLACE PARTITION` or, in rare cases, after `DETACH` or `DROP PARTITION`. It's fixed. [#15537](https://github.com/ClickHouse/ClickHouse/pull/15537) ([tavplubix](https://github.com/tavplubix)).
- Fix bug when `ILIKE` operator stops being case insensitive if `LIKE` with the same pattern was executed. [#15536](https://github.com/ClickHouse/ClickHouse/pull/15536) ([alesapin](https://github.com/alesapin)).
- Fix `Missing columns` errors when selecting columns which absent in data, but depend on other columns which also absent in data. Fixes [#15530](https://github.com/ClickHouse/ClickHouse/issues/15530). [#15532](https://github.com/ClickHouse/ClickHouse/pull/15532) ([alesapin](https://github.com/alesapin)).
- Throw an error when a single parameter is passed to ReplicatedMergeTree instead of ignoring it. [#15516](https://github.com/ClickHouse/ClickHouse/pull/15516) ([nvartolomei](https://github.com/nvartolomei)).
- Fix bug with event subscription in DDLWorker which rarely may lead to query hangs in `ON CLUSTER`. Introduced in [#13450](https://github.com/ClickHouse/ClickHouse/issues/13450). [#15477](https://github.com/ClickHouse/ClickHouse/pull/15477) ([alesapin](https://github.com/alesapin)).
- Report proper error when the second argument of `boundingRatio` aggregate function has a wrong type. [#15407](https://github.com/ClickHouse/ClickHouse/pull/15407) ([detailyang](https://github.com/detailyang)).
- Fixes [#15365](https://github.com/ClickHouse/ClickHouse/issues/15365): attach a database with MySQL engine throws exception (no query context). [#15384](https://github.com/ClickHouse/ClickHouse/pull/15384) ([Winter Zhang](https://github.com/zhang2014)).
- Fix the case of multiple occurrences of column transformers in a select query. [#15378](https://github.com/ClickHouse/ClickHouse/pull/15378) ([Amos Bird](https://github.com/amosbird)).
- Fixed compression in `S3` storage. [#15376](https://github.com/ClickHouse/ClickHouse/pull/15376) ([Vladimir Chebotarev](https://github.com/excitoon)).
- Fix bug where queries like `SELECT toStartOfDay(today())` fail complaining about empty time\_zone argument. [#15319](https://github.com/ClickHouse/ClickHouse/pull/15319) ([Bharat Nallan](https://github.com/bharatnc)).
- Fix race condition during MergeTree table rename and background cleanup. [#15304](https://github.com/ClickHouse/ClickHouse/pull/15304) ([alesapin](https://github.com/alesapin)).
- Fix rare race condition on server startup when system logs are enabled. [#15300](https://github.com/ClickHouse/ClickHouse/pull/15300) ([alesapin](https://github.com/alesapin)).
- Fix hang of queries with a lot of subqueries to same table of `MySQL` engine. Previously, if there were more than 16 subqueries to same `MySQL` table in query, it hang forever. [#15299](https://github.com/ClickHouse/ClickHouse/pull/15299) ([Anton Popov](https://github.com/CurtizJ)).
- Fix MSan report in QueryLog. Uninitialized memory can be used for the field `memory_usage`. [#15258](https://github.com/ClickHouse/ClickHouse/pull/15258) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fix 'Unknown identifier' in GROUP BY when query has JOIN over Merge table. [#15242](https://github.com/ClickHouse/ClickHouse/pull/15242) ([Artem Zuikov](https://github.com/4ertus2)).
- Fix instance crash when using `joinGet` with `LowCardinality` types. This fixes [#15214](https://github.com/ClickHouse/ClickHouse/issues/15214). [#15220](https://github.com/ClickHouse/ClickHouse/pull/15220) ([Amos Bird](https://github.com/amosbird)).
- Fix bug in table engine `Buffer` which does not allow to insert data of new structure into `Buffer` after `ALTER` query. Fixes [#15117](https://github.com/ClickHouse/ClickHouse/issues/15117). [#15192](https://github.com/ClickHouse/ClickHouse/pull/15192) ([alesapin](https://github.com/alesapin)).
- Adjust Decimal field size in MySQL column definition packet. [#15152](https://github.com/ClickHouse/ClickHouse/pull/15152) ([maqroll](https://github.com/maqroll)).
- Fixes `Data compressed with different methods` in `join_algorithm='auto'`. Keep LowCardinality as type for left table join key in `join_algorithm='partial_merge'`. [#15088](https://github.com/ClickHouse/ClickHouse/pull/15088) ([Artem Zuikov](https://github.com/4ertus2)).
- Update `jemalloc` to fix `percpu_arena` with affinity mask. [#15035](https://github.com/ClickHouse/ClickHouse/pull/15035) ([Azat Khuzhin](https://github.com/azat)). [#14957](https://github.com/ClickHouse/ClickHouse/pull/14957) ([Azat Khuzhin](https://github.com/azat)).
- We already use padded comparison between String and FixedString (<https://github.com/ClickHouse/ClickHouse/blob/master/src/Functions/FunctionsComparison.h#L333>). This PR applies the same logic to field comparison which corrects the usage of FixedString as primary keys. This fixes [#14908](https://github.com/ClickHouse/ClickHouse/issues/14908). [#15033](https://github.com/ClickHouse/ClickHouse/pull/15033) ([Amos Bird](https://github.com/amosbird)).
- If function `bar` was called with specifically crafted arguments, buffer overflow was possible. This closes [#13926](https://github.com/ClickHouse/ClickHouse/issues/13926). [#15028](https://github.com/ClickHouse/ClickHouse/pull/15028) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fixed `Cannot rename ... errno: 22, strerror: Invalid argument` error on DDL query execution in Atomic database when running clickhouse-server in Docker on Mac OS. [#15024](https://github.com/ClickHouse/ClickHouse/pull/15024) ([tavplubix](https://github.com/tavplubix)).
- Fix crash in RIGHT or FULL JOIN with join\_algorith='auto' when memory limit exceeded and we should change HashJoin with MergeJoin. [#15002](https://github.com/ClickHouse/ClickHouse/pull/15002) ([Artem Zuikov](https://github.com/4ertus2)).
- Now settings `number_of_free_entries_in_pool_to_execute_mutation` and `number_of_free_entries_in_pool_to_lower_max_size_of_merge` can be equal to `background_pool_size`. [#14975](https://github.com/ClickHouse/ClickHouse/pull/14975) ([alesapin](https://github.com/alesapin)).