2020 Changelog

### ClickHouse release v20.11.3.3-stable, 2020-11-13[​](#clickhouse-release-v201133-stable-2020-11-13 "Direct link to ClickHouse release v20.11.3.3-stable, 2020-11-13")

#### Bug Fix[​](#bug-fix-5 "Direct link to Bug Fix")

- Fix rare silent crashes when query profiler is on and ClickHouse is installed on OS with glibc version that has (supposedly) broken asynchronous unwind tables for some functions. This fixes [#15301](https://github.com/ClickHouse/ClickHouse/issues/15301). This fixes [#13098](https://github.com/ClickHouse/ClickHouse/issues/13098). [#16846](https://github.com/ClickHouse/ClickHouse/pull/16846) ([alexey-milovidov](https://github.com/alexey-milovidov)).

### ClickHouse release v20.11.2.1, 2020-11-11[​](#clickhouse-release-v201121-2020-11-11 "Direct link to ClickHouse release v20.11.2.1, 2020-11-11")

#### Backward Incompatible Change[​](#backward-incompatible-change-1 "Direct link to Backward Incompatible Change")

- If some `profile` was specified in `distributed_ddl` config section, then this profile could overwrite settings of `default` profile on server startup. It's fixed, now settings of distributed DDL queries should not affect global server settings. [#16635](https://github.com/ClickHouse/ClickHouse/pull/16635) ([tavplubix](https://github.com/tavplubix)).
- Restrict to use of non-comparable data types (like `AggregateFunction`) in keys (Sorting key, Primary key, Partition key, and so on). [#16601](https://github.com/ClickHouse/ClickHouse/pull/16601) ([alesapin](https://github.com/alesapin)).
- Remove `ANALYZE` and `AST` queries, and make the setting `enable_debug_queries` obsolete since now it is the part of full featured `EXPLAIN` query. [#16536](https://github.com/ClickHouse/ClickHouse/pull/16536) ([Ivan](https://github.com/abyss7)).
- Aggregate functions `boundingRatio`, `rankCorr`, `retention`, `timeSeriesGroupSum`, `timeSeriesGroupRateSum`, `windowFunnel` were erroneously made case-insensitive. Now their names are made case sensitive as designed. Only functions that are specified in SQL standard or made for compatibility with other DBMS or functions similar to those should be case-insensitive. [#16407](https://github.com/ClickHouse/ClickHouse/pull/16407) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Make `rankCorr` function return nan on insufficient data [#16124](https://github.com/ClickHouse/ClickHouse/issues/16124). [#16135](https://github.com/ClickHouse/ClickHouse/pull/16135) ([hexiaoting](https://github.com/hexiaoting)).
- When upgrading from versions older than 20.5, if rolling update is performed and cluster contains both versions 20.5 or greater and less than 20.5, if ClickHouse nodes with old versions are restarted and old version has been started up in presence of newer versions, it may lead to `Part ... intersects previous part` errors. To prevent this error, first install newer clickhouse-server packages on all cluster nodes and then do restarts (so, when clickhouse-server is restarted, it will start up with the new version).

#### New Feature[​](#new-feature-1 "Direct link to New Feature")

- Added support of LDAP as a user directory for locally non-existent users. [#12736](https://github.com/ClickHouse/ClickHouse/pull/12736) ([Denis Glazachev](https://github.com/traceon)).
- Add `system.replicated_fetches` table which shows currently running background fetches. [#16428](https://github.com/ClickHouse/ClickHouse/pull/16428) ([alesapin](https://github.com/alesapin)).
- Added setting `date_time_output_format`. [#15845](https://github.com/ClickHouse/ClickHouse/pull/15845) ([Maksim Kita](https://github.com/kitaisreal)).
- Added minimal web UI to ClickHouse. [#16158](https://github.com/ClickHouse/ClickHouse/pull/16158) ([alexey-milovidov](https://github.com/alexey-milovidov)).
- Allows to read/write Single protobuf message at once (w/o length-delimiters). [#15199](https://github.com/ClickHouse/ClickHouse/pull/15199) ([filimonov](https://github.com/filimonov)).
- Added initial OpenTelemetry support. ClickHouse now accepts OpenTelemetry traceparent headers over Native and HTTP protocols, and passes them downstream in some cases. The trace spans for executed queries are saved into the `system.opentelemetry_span_log` table. [#14195](https://github.com/ClickHouse/ClickHouse/pull/14195) ([Alexander Kuzmenkov](https://github.com/akuzm)).
- Allow specify primary key in column list of `CREATE TABLE` query. This is needed for compatibility with other SQL dialects. [#15823](https://github.com/ClickHouse/ClickHouse/pull/15823) ([Maksim Kita](https://github.com/kitaisreal)).
- Implement `OFFSET offset_row_count {ROW | ROWS} FETCH {FIRST | NEXT} fetch_row_count {ROW | ROWS} {ONLY | WITH TIES}` in SELECT query with ORDER BY. This is the SQL-standard way to specify `LIMIT`. [#15855](https://github.com/ClickHouse/ClickHouse/pull/15855) ([hexiaoting](https://github.com/hexiaoting)).
- `errorCodeToName` function - return variable name of the error (useful for analyzing query\_log and similar). `system.errors` table - shows how many times errors has been happened (respects `system_events_show_zero_values`). [#16438](https://github.com/ClickHouse/ClickHouse/pull/16438) ([Azat Khuzhin](https://github.com/azat)).
- Added function `untuple` which is a special function which can introduce new columns to the SELECT list by expanding a named tuple. [#16242](https://github.com/ClickHouse/ClickHouse/pull/16242) ([Nikolai Kochetov](https://github.com/KochetovNicolai), [Amos Bird](https://github.com/amosbird)).
- Now we can provide identifiers via query parameters. And these parameters can be used as table objects or columns. [#16594](https://github.com/ClickHouse/ClickHouse/pull/16594) ([Amos Bird](https://github.com/amosbird)).
- Added big integers (UInt256, Int128, Int256) and UUID data types support for MergeTree BloomFilter index. Big integers is an experimental feature. [#16642](https://github.com/ClickHouse/ClickHouse/pull/16642) ([Maksim Kita](https://github.com/kitaisreal)).
- Add `farmFingerprint64` function (non-cryptographic string hashing). [#16570](https://github.com/ClickHouse/ClickHouse/pull/16570) ([Jacob Hayes](https://github.com/JacobHayes)).
- Add `log_queries_min_query_duration_ms`, only queries slower than the value of this setting will go to `query_log`/`query_thread_log` (i.e. something like `slow_query_log` in mysql). [#16529](https://github.com/ClickHouse/ClickHouse/pull/16529) ([Azat Khuzhin](https://github.com/azat)).
- Ability to create a docker image on the top of `Alpine`. Uses precompiled binary and glibc components from ubuntu 20.04. [#16479](https://github.com/ClickHouse/ClickHouse/pull/16479) ([filimonov](https://github.com/filimonov)).
- Added `toUUIDOrNull`, `toUUIDOrZero` cast functions. [#16337](https://github.com/ClickHouse/ClickHouse/pull/16337) ([Maksim Kita](https://github.com/kitaisreal)).
- Add `max_concurrent_queries_for_all_users` setting, see [#6636](https://github.com/ClickHouse/ClickHouse/issues/6636) for use cases. [#16154](https://github.com/ClickHouse/ClickHouse/pull/16154) ([nvartolomei](https://github.com/nvartolomei)).
- Add a new option `print_query_id` to clickhouse-client. It helps generate arbitrary strings with the current query id generated by the client. Also print query id in clickhouse-client by default. [#15809](https://github.com/ClickHouse/ClickHouse/pull/15809) ([Amos Bird](https://github.com/amosbird)).
- Add `tid` and `logTrace` functions. This closes [#9434](https://github.com/ClickHouse/ClickHouse/issues/9434). [#15803](https://github.com/ClickHouse/ClickHouse/pull/15803) ([flynn](https://github.com/ucasFL)).
- Add function `formatReadableTimeDelta` that format time delta to human readable string ... [#15497](https://github.com/ClickHouse/ClickHouse/pull/15497) ([Filipe Caixeta](https://github.com/filipecaixeta)).
- Added `disable_merges` option for volumes in multi-disk configuration. [#13956](https://github.com/ClickHouse/ClickHouse/pull/13956) ([Vladimir Chebotarev](https://github.com/excitoon)).

#### Experimental Feature[​](#experimental-feature-1 "Direct link to Experimental Feature")