2021 Changelog

- Previously progress was shown only for `numbers` table function. Now for `numbers_mt` it is also shown. [#31318](https://github.com/ClickHouse/ClickHouse/pull/31318) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Initial user's roles are used now to find row policies, see [#31080](https://github.com/ClickHouse/ClickHouse/issues/31080). [#31262](https://github.com/ClickHouse/ClickHouse/pull/31262) ([Vitaly Baranov](https://github.com/vitlibar)).
- If some obsolete setting is changed - show warning in `system.warnings`. [#31252](https://github.com/ClickHouse/ClickHouse/pull/31252) ([tavplubix](https://github.com/tavplubix)).
- Improved backoff for background cleanup tasks in `MergeTree`. Settings `merge_tree_clear_old_temporary_directories_interval_seconds` and `merge_tree_clear_old_parts_interval_seconds` moved from users settings to merge tree settings. [#31180](https://github.com/ClickHouse/ClickHouse/pull/31180) ([tavplubix](https://github.com/tavplubix)).
- Now every replica will send to client only incremental information about profile events counters. [#31155](https://github.com/ClickHouse/ClickHouse/pull/31155) ([Dmitry Novik](https://github.com/novikd)). This makes `--hardware_utilization` option in `clickhouse-client` usable.
- Enable multiline editing in clickhouse-client by default. This addresses [#31121](https://github.com/ClickHouse/ClickHouse/issues/31121) . [#31123](https://github.com/ClickHouse/ClickHouse/pull/31123) ([Amos Bird](https://github.com/amosbird)).
- Function name normalization for `ALTER` queries. This helps avoid metadata mismatch between creating table with indices/projections and adding indices/projections via alter commands. This is a follow-up PR of <https://github.com/ClickHouse/ClickHouse/pull/20174>. Mark as improvements as there are no bug reports and the senario is somehow rare. [#31095](https://github.com/ClickHouse/ClickHouse/pull/31095) ([Amos Bird](https://github.com/amosbird)).
- Support `IF EXISTS` modifier for `RENAME DATABASE`/`TABLE`/`DICTIONARY` query. If this directive is used, one will not get an error if the DATABASE/TABLE/DICTIONARY to be renamed doesn't exist. [#31081](https://github.com/ClickHouse/ClickHouse/pull/31081) ([victorgao](https://github.com/kafka1991)).
- Cancel vertical merges when partition is dropped. This is a follow-up of <https://github.com/ClickHouse/ClickHouse/pull/25684> and <https://github.com/ClickHouse/ClickHouse/pull/30996>. [#31057](https://github.com/ClickHouse/ClickHouse/pull/31057) ([Amos Bird](https://github.com/amosbird)).
- The local session inside a ClickHouse dictionary source won't send its events to the session log anymore. This fixes a possible deadlock (tsan alert) on shutdown. Also this PR fixes flaky `test_dictionaries_dependency_xml/`. [#31013](https://github.com/ClickHouse/ClickHouse/pull/31013) ([Vitaly Baranov](https://github.com/vitlibar)).
- Less locking in ALTER command. [#31010](https://github.com/ClickHouse/ClickHouse/pull/31010) ([Amos Bird](https://github.com/amosbird)).
- Fix `--verbose` option in clickhouse-local interactive mode and allow logging into file. [#30881](https://github.com/ClickHouse/ClickHouse/pull/30881) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Added `\l`, `\d`, `\c` commands in `clickhouse-client` like in MySQL and PostgreSQL. [#30876](https://github.com/ClickHouse/ClickHouse/pull/30876) ([Pavel Medvedev](https://github.com/pmed)).
- For clickhouse-local or clickhouse-client: if there is `--interactive` option with `--query` or `--queries-file`, then first execute them like in non-interactive and then start interactive mode. [#30851](https://github.com/ClickHouse/ClickHouse/pull/30851) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Fix possible "The local set of parts of X doesn't look like the set of parts in ZooKeeper" error (if DROP fails during removing znodes from zookeeper). [#30826](https://github.com/ClickHouse/ClickHouse/pull/30826) ([Azat Khuzhin](https://github.com/azat)).
- Avro format works against Kafka. Setting `output_format_avro_rows_in_file` added. [#30351](https://github.com/ClickHouse/ClickHouse/pull/30351) ([Ilya Golshtein](https://github.com/ilejn)).
- Allow to specify one or any number of PostgreSQL schemas for one `MaterializedPostgreSQL` database. Closes [#28901](https://github.com/ClickHouse/ClickHouse/issues/28901). Closes [#29324](https://github.com/ClickHouse/ClickHouse/issues/29324). [#28933](https://github.com/ClickHouse/ClickHouse/pull/28933) ([Kseniia Sumarokova](https://github.com/kssenii)).
- Replaced default ports for clickhouse-keeper internal communication from 44444 to 9234. Fixes [#30879](https://github.com/ClickHouse/ClickHouse/issues/30879). [#31799](https://github.com/ClickHouse/ClickHouse/pull/31799) ([alesapin](https://github.com/alesapin)).
- Implement function transform with Decimal arguments. [#31839](https://github.com/ClickHouse/ClickHouse/pull/31839) ([李帅](https://github.com/loneylee)).
- Fix abort in debug server and `DB::Exception: std::out_of_range: basic_string` error in release server in case of bad hdfs url by adding additional check of hdfs url structure. [#31042](https://github.com/ClickHouse/ClickHouse/pull/31042) ([Kruglov Pavel](https://github.com/Avogar)).
- Fix possible assert in `hdfs` table function/engine, add test. [#31036](https://github.com/ClickHouse/ClickHouse/pull/31036) ([Kruglov Pavel](https://github.com/Avogar)).