2019 Changelog

#### Backward Incompatible Change[​](#backward-incompatible-change-8 "Direct link to Backward Incompatible Change")

- Rename setting `insert_sample_with_metadata` to setting `input_format_defaults_for_omitted_fields`. [#4771](https://github.com/ClickHouse/ClickHouse/pull/4771) ([Artem Zuikov](https://github.com/4ertus2))
- Added setting `max_partitions_per_insert_block` (with value 100 by default). If inserted block contains larger number of partitions, an exception is thrown. Set it to 0 if you want to remove the limit (not recommended). [#4845](https://github.com/ClickHouse/ClickHouse/pull/4845) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Multi-search functions were renamed (`multiPosition` to `multiSearchAllPositions`, `multiSearch` to `multiSearchAny`, `firstMatch` to `multiSearchFirstIndex`). [#4780](https://github.com/ClickHouse/ClickHouse/pull/4780) ([Danila Kutenin](https://github.com/danlark1))

#### Performance Improvement[​](#performance-improvement-6 "Direct link to Performance Improvement")

- Optimize Volnitsky searcher by inlining, giving about 5-10% search improvement for queries with many needles or many similar bigrams. [#4862](https://github.com/ClickHouse/ClickHouse/pull/4862) ([Danila Kutenin](https://github.com/danlark1))
- Fix performance issue when setting `use_uncompressed_cache` is greater than zero, which appeared when all read data contained in cache. [#4913](https://github.com/ClickHouse/ClickHouse/pull/4913) ([alesapin](https://github.com/alesapin))

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-10 "Direct link to Build/Testing/Packaging Improvement")

- Hardening debug build: more granular memory mappings and ASLR; add memory protection for mark cache and index. This allows to find more memory stomping bugs in case when ASan and MSan cannot do it. [#4632](https://github.com/ClickHouse/ClickHouse/pull/4632) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Add support for cmake variables `ENABLE_PROTOBUF`, `ENABLE_PARQUET` and `ENABLE_BROTLI` which allows to enable/disable the above features (same as we can do for librdkafka, mysql, etc). [#4669](https://github.com/ClickHouse/ClickHouse/pull/4669) ([Silviu Caragea](https://github.com/silviucpp))
- Add ability to print process list and stacktraces of all threads if some queries are hung after test run. [#4675](https://github.com/ClickHouse/ClickHouse/pull/4675) ([alesapin](https://github.com/alesapin))
- Add retries on `Connection loss` error in `clickhouse-test`. [#4682](https://github.com/ClickHouse/ClickHouse/pull/4682) ([alesapin](https://github.com/alesapin))
- Add freebsd build with vagrant and build with thread sanitizer to packager script. [#4712](https://github.com/ClickHouse/ClickHouse/pull/4712) [#4748](https://github.com/ClickHouse/ClickHouse/pull/4748) ([alesapin](https://github.com/alesapin))
- Now user asked for password for user `'default'` during installation. [#4725](https://github.com/ClickHouse/ClickHouse/pull/4725) ([proller](https://github.com/proller))
- Suppress warning in `rdkafka` library. [#4740](https://github.com/ClickHouse/ClickHouse/pull/4740) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Allow ability to build without ssl. [#4750](https://github.com/ClickHouse/ClickHouse/pull/4750) ([proller](https://github.com/proller))
- Add a way to launch clickhouse-server image from a custom user. [#4753](https://github.com/ClickHouse/ClickHouse/pull/4753) ([Mikhail f. Shiryaev](https://github.com/Felixoid))
- Upgrade contrib boost to 1.69. [#4793](https://github.com/ClickHouse/ClickHouse/pull/4793) ([proller](https://github.com/proller))
- Disable usage of `mremap` when compiled with Thread Sanitizer. Surprisingly enough, TSan does not intercept `mremap` (though it does intercept `mmap`, `munmap`) that leads to false positives. Fixed TSan report in stateful tests. [#4859](https://github.com/ClickHouse/ClickHouse/pull/4859) ([alexey-milovidov](https://github.com/alexey-milovidov))
- Add test checking using format schema via HTTP interface. [#4864](https://github.com/ClickHouse/ClickHouse/pull/4864) ([Vitaly Baranov](https://github.com/vitlibar))

## ClickHouse Release 19.4[​](#clickhouse-release-19-4 "Direct link to ClickHouse Release 19.4")

### ClickHouse Release 19.4.4.33, 2019-04-17[​](#clickhouse-release-19-4-4-33-2019-04-17 "Direct link to ClickHouse Release 19.4.4.33, 2019-04-17")

#### Bug Fixes[​](#bug-fixes-7 "Direct link to Bug Fixes")