2020 Changelog

### ClickHouse release v20.1.12.86, 2020-05-26[​](#clickhouse-release-v2011286-2020-05-26 "Direct link to ClickHouse release v20.1.12.86, 2020-05-26")

#### Bug Fix[​](#bug-fix-54 "Direct link to Bug Fix")

- Fixed incompatibility of two-level aggregation between versions 20.1 and earlier. This incompatibility happens when different versions of ClickHouse are used on initiator node and remote nodes and the size of GROUP BY result is large and aggregation is performed by a single String field. It leads to several unmerged rows for a single key in result. [#10952](https://github.com/ClickHouse/ClickHouse/pull/10952) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fixed data corruption for `LowCardinality(FixedString)` key column in `SummingMergeTree` which could have happened after merge. Fixes [#10489](https://github.com/ClickHouse/ClickHouse/issues/10489). [#10721](https://github.com/ClickHouse/ClickHouse/pull/10721) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fixed bug, which causes http requests stuck on client close when `readonly=2` and `cancel_http_readonly_queries_on_client_close=1`. Fixes [#7939](https://github.com/ClickHouse/ClickHouse/issues/7939), [#7019](https://github.com/ClickHouse/ClickHouse/issues/7019), [#7736](https://github.com/ClickHouse/ClickHouse/issues/7736), [#7091](https://github.com/ClickHouse/ClickHouse/issues/7091). [#10684](https://github.com/ClickHouse/ClickHouse/pull/10684) ([tavplubix](https://github.com/tavplubix)).
- Fixed a bug when on `SYSTEM DROP DNS CACHE` query also drop caches, which are used to check if user is allowed to connect from some IP addresses. [#10608](https://github.com/ClickHouse/ClickHouse/pull/10608) ([tavplubix](https://github.com/tavplubix)).
- Fixed incorrect scalar results inside inner query of `MATERIALIZED VIEW` in case if this query contained dependent table. [#10603](https://github.com/ClickHouse/ClickHouse/pull/10603) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fixed the situation when mutation finished all parts, but hung up in `is_done=0`. [#10526](https://github.com/ClickHouse/ClickHouse/pull/10526) ([alesapin](https://github.com/alesapin)).
- Fixed overflow at beginning of unix epoch for timezones with fractional offset from UTC. This fixes [#9335](https://github.com/ClickHouse/ClickHouse/issues/9335). [#10513](https://github.com/ClickHouse/ClickHouse/pull/10513) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fixed improper shutdown of Distributed storage. [#10491](https://github.com/ClickHouse/ClickHouse/pull/10491) ([Azat Khuzhin](https://github.com/azat)).
- Fixed numeric overflow in `simpleLinearRegression` over large integers. [#10474](https://github.com/ClickHouse/ClickHouse/pull/10474) ([hcz](https://github.com/hczhcz)).
- Fixed removing metadata directory when attach database fails. [#10442](https://github.com/ClickHouse/ClickHouse/pull/10442) ([Winter Zhang](https://github.com/zhang2014)).
- Added a check of number and type of arguments when creating `BloomFilter` index [#9623](https://github.com/ClickHouse/ClickHouse/issues/9623). [#10431](https://github.com/ClickHouse/ClickHouse/pull/10431) ([Winter Zhang](https://github.com/zhang2014)).
- Fixed the issue when a query with `ARRAY JOIN`, `ORDER BY` and `LIMIT` may return incomplete result. This fixes [#10226](https://github.com/ClickHouse/ClickHouse/issues/10226). [#10427](https://github.com/ClickHouse/ClickHouse/pull/10427) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Prefer `fallback_to_stale_replicas` over `skip_unavailable_shards`. [#10422](https://github.com/ClickHouse/ClickHouse/pull/10422) ([Azat Khuzhin](https://github.com/azat)).
- Fixed wrong flattening of `Array(Tuple(...))` data types. This fixes [#10259](https://github.com/ClickHouse/ClickHouse/issues/10259). [#10390](https://github.com/ClickHouse/ClickHouse/pull/10390) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Fixed wrong behavior in `HashTable` that caused compilation error when trying to read HashMap from buffer. [#10386](https://github.com/ClickHouse/ClickHouse/pull/10386) ([palasonic1](https://github.com/palasonic1)).
- Fixed possible `Pipeline stuck` error in `ConcatProcessor` which could have happened in remote query. [#10381](https://github.com/ClickHouse/ClickHouse/pull/10381) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fixed error `Pipeline stuck` with `max_rows_to_group_by` and `group_by_overflow_mode = 'break'`. [#10279](https://github.com/ClickHouse/ClickHouse/pull/10279) ([Nikolai Kochetov](https://github.com/KochetovNicolai)).
- Fixed several bugs when some data was inserted with quorum, then deleted somehow (DROP PARTITION, TTL) and this leaded to the stuck of INSERTs or false-positive exceptions in SELECTs. This fixes [#9946](https://github.com/ClickHouse/ClickHouse/issues/9946). [#10188](https://github.com/ClickHouse/ClickHouse/pull/10188) ([Nikita Mikhaylov](https://github.com/nikitamikhaylov)).
- Fixed incompatibility when versions prior to 18.12.17 are used on remote servers and newer is used on initiating server, and GROUP BY both fixed and non-fixed keys, and when two-level group by method is activated. [#3254](https://github.com/ClickHouse/ClickHouse/pull/3254) ([alexey-milovidov](https://github.com/alexey-milovidov)).

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-21 "Direct link to Build/Testing/Packaging Improvement")

- Added CA certificates to clickhouse-server docker image. [#10476](https://github.com/ClickHouse/ClickHouse/pull/10476) ([filimonov](https://github.com/filimonov)).

### ClickHouse release v20.1.10.70, 2020-04-17[​](#clickhouse-release-v2011070-2020-04-17 "Direct link to ClickHouse release v20.1.10.70, 2020-04-17")

#### Bug Fix[​](#bug-fix-55 "Direct link to Bug Fix")