2021 Changelog

- Use old modulo function version when used in partition key and primary key. Closes [#23508](https://github.com/ClickHouse/ClickHouse/issues/23508). [#24157](https://github.com/ClickHouse/ClickHouse/pull/24157) ([Kseniia Sumarokova](https://github.com/kssenii)). It was a source of backward incompatibility in previous releases.
- Fixed the behavior when query `SYSTEM RESTART REPLICA` or `SYSTEM SYNC REPLICA` is being processed infinitely. This was detected on server with extremely little amount of RAM. [#24457](https://github.com/ClickHouse/ClickHouse/pull/24457) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
- Fix incorrect monotonicity of `toWeek` function. This fixes [#24422](https://github.com/ClickHouse/ClickHouse/issues/24422) . This bug was introduced in [#5212](https://github.com/ClickHouse/ClickHouse/pull/5212), and was exposed later by smarter partition pruner. [#24446](https://github.com/ClickHouse/ClickHouse/pull/24446) ([Amos Bird](https://github.com/amosbird)).
- Fix drop partition with intersect fake parts. In rare cases there might be parts with mutation version greater than current block number. [#24321](https://github.com/ClickHouse/ClickHouse/pull/24321) ([Amos Bird](https://github.com/amosbird)).
- Fixed a bug in moving materialized view from Ordinary to Atomic database (`RENAME TABLE` query). Now inner table is moved to new database together with materialized view. Fixes [#23926](https://github.com/ClickHouse/ClickHouse/issues/23926). [#24309](https://github.com/ClickHouse/ClickHouse/pull/24309) ([tavplubix](https://github.com/tavplubix)).
- Allow empty HTTP headers in client requests. Fixes [#23901](https://github.com/ClickHouse/ClickHouse/issues/23901). [#24285](https://github.com/ClickHouse/ClickHouse/pull/24285) ([Ivan](https://github.com/abyss7)).
- Set `max_threads = 1` to fix mutation fail of `Memory` tables. Closes [#24274](https://github.com/ClickHouse/ClickHouse/issues/24274). [#24275](https://github.com/ClickHouse/ClickHouse/pull/24275) ([flynn](https://github.com/ucasFL)).
- Fix typo in implementation of `Memory` tables, this bug was introduced at [#15127](https://github.com/ClickHouse/ClickHouse/issues/15127). Closes [#24192](https://github.com/ClickHouse/ClickHouse/issues/24192). [#24193](https://github.com/ClickHouse/ClickHouse/pull/24193) ([张中南](https://github.com/plugine)).
- Fix abnormal server termination due to `HDFS` becoming not accessible during query execution. Closes [#24117](https://github.com/ClickHouse/ClickHouse/issues/24117). [#24191](https://github.com/ClickHouse/ClickHouse/pull/24191) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Fix crash on updating of `Nested` column with const condition. [#24183](https://github.com/ClickHouse/ClickHouse/pull/24183) ([hexiaoting](https://github.com/hexiaoting)).
- Fix race condition which could happen in RBAC under a heavy load. This PR fixes [#24090](https://github.com/ClickHouse/ClickHouse/issues/24090), [#24134](https://github.com/ClickHouse/ClickHouse/issues/24134),. [#24176](https://github.com/ClickHouse/ClickHouse/pull/24176) ([Vitaly Baranov](https://github.com/vitlibar)).
- Fix a rare bug that could lead to a partially initialized table that can serve write requests (insert/alter/so on). Now such tables will be in readonly mode. [#24122](https://github.com/ClickHouse/ClickHouse/pull/24122) ([alesapin](https://github.com/alesapin)).
- Fix an issue: `EXPLAIN PIPELINE` with `SELECT xxx FINAL` showed a wrong pipeline. ([hexiaoting](https://github.com/hexiaoting)).
- Fixed using const `DateTime` value vs `DateTime64` column in `WHERE`. [#24100](https://github.com/ClickHouse/ClickHouse/pull/24100) ([Vasily Nemkov](https://github.com/Enmk)).
- Fix crash in merge JOIN, closes [#24010](https://github.com/ClickHouse/ClickHouse/issues/24010). [#24013](https://github.com/ClickHouse/ClickHouse/pull/24013) ([vdimir](https://github.com/vdimir)).
- Some `ALTER PARTITION` queries might cause `Part A intersects previous part B` and `Unexpected merged part C intersecting drop range D` errors in replication queue. It's fixed. Fixes [#23296](https://github.com/ClickHouse/ClickHouse/issues/23296). [#23997](https://github.com/ClickHouse/ClickHouse/pull/23997) ([tavplubix](https://github.com/tavplubix)).
- Fix SIGSEGV for external GROUP BY and overflow row (i.e. queries like `SELECT FROM GROUP BY WITH TOTALS SETTINGS max_bytes_before_external_group_by>0, max_rows_to_group_by>0, group_by_overflow_mode='any', totals_mode='before_having'`). [#23962](https://github.com/ClickHouse/ClickHouse/pull/23962) ([Azat Khuzhin](https://github.com/azat)).
- Fix keys metrics accounting for `CACHE` dictionary with duplicates in the source (leads to `DictCacheKeysRequestedMiss` overflows). [#23929](https://github.com/ClickHouse/ClickHouse/pull/23929) ([Azat Khuzhin](https://github.com/azat)).
- Fix implementation of connection pool of `PostgreSQL` engine. Closes [#23897](https://github.com/ClickHouse/ClickHouse/issues/23897). [#23909](https://github.com/ClickHouse/ClickHouse/pull/23909) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Fix `distributed_group_by_no_merge = 2` with `GROUP BY` and aggregate function wrapped into regular function (had been broken in [#23546](https://github.com/ClickHouse/ClickHouse/issues/23546)). Throw exception in case of someone trying to use `distributed_group_by_no_merge = 2` with window functions. Disable `optimize_distributed_group_by_sharding_key` for queries with window functions. [#23906](https://github.com/ClickHouse/ClickHouse/pull/23906) ([Azat Khuzhin](https://github.com/azat)).
- A fix for `s3` table function: better handling of HTTP errors. Response bodies of HTTP errors were being ignored earlier. [#23844](https://github.com/ClickHouse/ClickHouse/pull/23844) ([Vladimir Chebotarev](https://github.com/excitoon)).
- A fix for `s3` table function: better handling of URI's. Fixed an incompatibility with URLs containing `+` symbol, data with such keys could not be read previously. [#23822](https://github.com/ClickHouse/ClickHouse/pull/23822) ([Vladimir Chebotarev](https://github.com/excitoon)).
- Fix error `Can't initialize pipeline with empty pipe` for queries with `GLOBAL IN/JOIN` and `use_hedged_requests`. Fixes [#23431](https://github.com/ClickHouse/ClickHouse/issues/23431). [#23805](https://github.com/ClickHouse/ClickHouse/pull/23805) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fix `CLEAR COLUMN` does not work when it is referenced by materialized view. Close [#23764](https://github.com/ClickHouse/ClickHouse/issues/23764). [#23781](https://github.com/ClickHouse/ClickHouse/pull/23781) ([flynn](https://github.com/ucasFL)).
- Fix heap use after free when reading from HDFS if `Values` format is used. [#23761](https://github.com/ClickHouse/ClickHouse/pull/23761) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Avoid possible "Cannot schedule a task" error (in case some exception had been occurred) on INSERT into Distributed. [#23744](https://github.com/ClickHouse/ClickHouse/pull/23744) ([Azat Khuzhin](https://github.com/azat)).
- Fixed a bug in recovery of staled `ReplicatedMergeTree` replica. Some metadata updates could be ignored by staled replica if `ALTER` query was executed during downtime of the replica. [#23742](https://github.com/ClickHouse/ClickHouse/pull/23742) ([tavplubix](https://github.com/tavplubix)).
- Fix a bug with `Join` and `WITH TOTALS`, close [#17718](https://github.com/ClickHouse/ClickHouse/issues/17718). [#23549](https://github.com/ClickHouse/ClickHouse/pull/23549) ([vdimir](https://github.com/vdimir)).
- Fix possible `Block structure mismatch` error for queries with `UNION` which could possibly happen after filter-pushdown optimization. Fixes [#23029](https://github.com/ClickHouse/ClickHouse/issues/23029). [#23359](https://github.com/ClickHouse/ClickHouse/pull/23359) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Add type conversion when the setting `optimize_skip_unused_shards_rewrite_in` is enabled. This fixes MSan report. [#23219](https://github.com/ClickHouse/ClickHouse/pull/23219) ([Azat Khuzhin](https://github.com/azat)).