2019 Changelog

- Remove Compiler (runtime template instantiation) because we've win over it's performance. [#6646](https://github.com/ClickHouse/ClickHouse/pull/6646) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Added performance test to show degradation of performance in gcc-9 in more isolated way. [#6302](https://github.com/ClickHouse/ClickHouse/pull/6302) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Added table function `numbers_mt`, which is multi-threaded version of `numbers`. Updated performance tests with hash functions. [#6554](https://github.com/ClickHouse/ClickHouse/pull/6554) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
- Comparison mode in `clickhouse-benchmark` [#6220](https://github.com/ClickHouse/ClickHouse/issues/6220) [#6343](https://github.com/ClickHouse/ClickHouse/pull/6343) ([dimarub2000](https://github.com/dimarub2000))
- Best effort for printing stack traces. Also added `SIGPROF` as a debugging signal to print stack trace of a running thread. [#6529](https://github.com/ClickHouse/ClickHouse/pull/6529) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Every function in its own file, part 10. [#6321](https://github.com/ClickHouse/ClickHouse/pull/6321) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Remove doubled const `TABLE_IS_READ_ONLY`. [#6566](https://github.com/ClickHouse/ClickHouse/pull/6566) ([filimonov](https://github.com/filimonov))
- Formatting changes for `StringHashMap` PR [#5417](https://github.com/ClickHouse/ClickHouse/issues/5417). [#6700](https://github.com/ClickHouse/ClickHouse/pull/6700) ([akuzm](https://github.com/akuzm))
- Better subquery for join creation in `ExpressionAnalyzer`. [#6824](https://github.com/ClickHouse/ClickHouse/pull/6824) ([Artem Zuikov](https://github.com/4ertus2))
- Remove a redundant condition (found by PVS Studio). [#6775](https://github.com/ClickHouse/ClickHouse/pull/6775) ([akuzm](https://github.com/akuzm))
- Separate the hash table interface for `ReverseIndex`. [#6672](https://github.com/ClickHouse/ClickHouse/pull/6672) ([akuzm](https://github.com/akuzm))
- Refactoring of settings. [#6689](https://github.com/ClickHouse/ClickHouse/pull/6689) ([alesapin](https://github.com/alesapin))
- Add comments for `set` index functions. [#6319](https://github.com/ClickHouse/ClickHouse/pull/6319) ([Nikita Vasilev](https://github.com/nikvas0))
- Increase OOM score in debug version on Linux. [#6152](https://github.com/ClickHouse/ClickHouse/pull/6152) ([akuzm](https://github.com/akuzm))
- HDFS HA now work in debug build. [#6650](https://github.com/ClickHouse/ClickHouse/pull/6650) ([Weiqing Xu](https://github.com/weiqxu))
- Added a test to `transform_query_for_external_database`. [#6388](https://github.com/ClickHouse/ClickHouse/pull/6388) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Add test for multiple materialized views for Kafka table. [#6509](https://github.com/ClickHouse/ClickHouse/pull/6509) ([Ivan](https://github.com/abyss7))
- Make a better build scheme. [#6500](https://github.com/ClickHouse/ClickHouse/pull/6500) ([Ivan](https://github.com/abyss7))
- Fixed `test_external_dictionaries` integration in case it was executed under non root user. [#6507](https://github.com/ClickHouse/ClickHouse/pull/6507) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
- The bug reproduces when total size of written packets exceeds `DBMS_DEFAULT_BUFFER_SIZE`. [#6204](https://github.com/ClickHouse/ClickHouse/pull/6204) ([Yuriy Baranov](https://github.com/yurriy))
- Added a test for `RENAME` table race condition [#6752](https://github.com/ClickHouse/ClickHouse/pull/6752) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Avoid data race on Settings in `KILL QUERY`. [#6753](https://github.com/ClickHouse/ClickHouse/pull/6753) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Add integration test for handling errors by a cache dictionary. [#6755](https://github.com/ClickHouse/ClickHouse/pull/6755) ([Vitaly Baranov](https://github.com/vitlibar))
- Disable parsing of ELF object files on Mac OS, because it makes no sense. [#6578](https://github.com/ClickHouse/ClickHouse/pull/6578) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Attempt to make changelog generator better. [#6327](https://github.com/ClickHouse/ClickHouse/pull/6327) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Adding `-Wshadow` switch to the GCC. [#6325](https://github.com/ClickHouse/ClickHouse/pull/6325) ([kreuzerkrieg](https://github.com/kreuzerkrieg))
- Removed obsolete code for `mimalloc` support. [#6715](https://github.com/ClickHouse/ClickHouse/pull/6715) ([alexey-milovidov](https://github.com/alexey-milovidov))
- `zlib-ng` determines x86 capabilities and saves this info to global variables. This is done in defalteInit call, which may be made by different threads simultaneously. To avoid multi-threaded writes, do it on library startup. [#6141](https://github.com/ClickHouse/ClickHouse/pull/6141) ([akuzm](https://github.com/akuzm))
- Regression test for a bug which in join which was fixed in [#5192](https://github.com/ClickHouse/ClickHouse/issues/5192). [#6147](https://github.com/ClickHouse/ClickHouse/pull/6147) ([Bakhtiyor Ruziev](https://github.com/theruziev))
- Fixed MSan report. [#6144](https://github.com/ClickHouse/ClickHouse/pull/6144) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Fix flapping TTL test. [#6782](https://github.com/ClickHouse/ClickHouse/pull/6782) ([Anton Popov](https://github.com/CurtizJ))
- Fixed false data race in `MergeTreeDataPart::is_frozen` field. [#6583](https://github.com/ClickHouse/ClickHouse/pull/6583) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Fixed timeouts in fuzz test. In previous version, it managed to find false hangup in query `SELECT * FROM numbers_mt(gccMurmurHash(''))`. [#6582](https://github.com/ClickHouse/ClickHouse/pull/6582) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Added debug checks to `static_cast` of columns. [#6581](https://github.com/ClickHouse/ClickHouse/pull/6581) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Support for Oracle Linux in official RPM packages. [#6356](https://github.com/ClickHouse/ClickHouse/issues/6356) [#6585](https://github.com/ClickHouse/ClickHouse/pull/6585) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Changed json perftests from `once` to `loop` type. [#6536](https://github.com/ClickHouse/ClickHouse/pull/6536) ([Nikolai Kochetov](https://github.com/KochetovNicolai))
- `odbc-bridge.cpp` defines `main()` so it should not be included in `clickhouse-lib`. [#6538](https://github.com/ClickHouse/ClickHouse/pull/6538) ([Orivej Desh](https://github.com/orivej))
- Test for crash in `FULL|RIGHT JOIN` with nulls in right table's keys. [#6362](https://github.com/ClickHouse/ClickHouse/pull/6362) ([Artem Zuikov](https://github.com/4ertus2))
- Added a test for the limit on expansion of aliases just in case. [#6442](https://github.com/ClickHouse/ClickHouse/pull/6442) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Switched from `boost::filesystem` to `std::filesystem` where appropriate. [#6253](https://github.com/ClickHouse/ClickHouse/pull/6253) [#6385](https://github.com/ClickHouse/ClickHouse/pull/6385) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Added RPM packages to website. [#6251](https://github.com/ClickHouse/ClickHouse/pull/6251) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Add a test for fixed `Unknown identifier` exception in `IN` section. [#6708](https://github.com/ClickHouse/ClickHouse/pull/6708) ([Artem Zuikov](https://github.com/4ertus2))
- Simplify `shared_ptr_helper` because people facing difficulties understanding it. [#6675](https://github.com/ClickHouse/ClickHouse/pull/6675) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Added performance tests for fixed Gorilla and DoubleDelta codec. [#6179](https://github.com/ClickHouse/ClickHouse/pull/6179) ([Vasily Nemkov](https://github.com/Enmk))