Changelog 2026

#### Build/Testing/Packaging Improvement[​](#buildtestingpackaging-improvement-1 "Direct link to Build/Testing/Packaging Improvement")

- ClickHouse can be built with clang-23 (master). [#95578](https://github.com/ClickHouse/ClickHouse/pull/95578) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Fix force `is_local` to false when `bind_host` is configured and replace with integration test. Follow-up for [#74741](https://github.com/ClickHouse/ClickHouse/pull/74741). [#93109](https://github.com/ClickHouse/ClickHouse/pull/93109) [#96018](https://github.com/ClickHouse/ClickHouse/pull/96018) ([Zhigao Hong](https://github.com/zghong)).
- Stress tests: fix stress and upgrade tests in CI. ignore `no-{build}` tags. add compatibility randomization. [#94693](https://github.com/ClickHouse/ClickHouse/pull/94693) ([Nikita Fomichev](https://github.com/fm4v)).
- Publish parser\_memory\_profiler binary from build. Tool can be used to analyze AST memory consumption. [#95826](https://github.com/ClickHouse/ClickHouse/pull/95826) ([Ilya Yatsishin](https://github.com/qoega)).
- Add `--symbolize` flag for `parser_memory_profiler` tool that produces `.heap.sym` files with resolved symbols in results. [#96477](https://github.com/ClickHouse/ClickHouse/pull/96477) ([Ilya Yatsishin](https://github.com/qoega)).
- Pin third-party Docker images in integration tests to specific versions. [#96500](https://github.com/ClickHouse/ClickHouse/pull/96500) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Restore the possibility to link `OpenSSL` dynamically. This is not recommended and not used by any production builds, but the option still exists for enthusiasts on the Internet. [#96506](https://github.com/ClickHouse/ClickHouse/pull/96506) ([Govind R Nair](https://github.com/Revertionist)).
- Reduce `magic_enum` range from [-100, 1000] to default [-128, 127] by using a per-type specialization for `Coordination::OpNum`, improving build time. [#96632](https://github.com/ClickHouse/ClickHouse/pull/96632) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Remove unnecessary C++ templates from Function classes to reduce build times. [#96646](https://github.com/ClickHouse/ClickHouse/pull/96646) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Move `StorageSystemLicenses` generation to configure time to improve build parallelism. [#96697](https://github.com/ClickHouse/ClickHouse/pull/96697) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Parallelize license scanning. [#96727](https://github.com/ClickHouse/ClickHouse/pull/96727) ([Raúl Marín](https://github.com/Algunenano)).
- Add stateless functional test for SSH protocol support. [#96996](https://github.com/ClickHouse/ClickHouse/pull/96996) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add Kafka 3.9.0 to the stateless functional test infrastructure, enabling direct testing of Kafka and Kafka2 table engines using ClickHouse Keeper as ZooKeeper. Six new stateless tests cover basic produce/consume, virtual columns, INSERT, multiple formats, broken message handling, and Keeper-based offset storage. [#96997](https://github.com/ClickHouse/ClickHouse/pull/96997) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Add a CI workflow to build PGO+BOLT optimized clang toolchain. [#96991](https://github.com/ClickHouse/ClickHouse/pull/96991) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Use the PGO-optimized LLVM/Clang build in CI, which should give 20..30% build speed improvement. [#97031](https://github.com/ClickHouse/ClickHouse/pull/97031) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Replace math functions from glibc with llvm-libc implementations. [#90151](https://github.com/ClickHouse/ClickHouse/pull/90151) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Update Boost from 1.83 to 1.90, fixing a `devector` assertion failure in debug builds. [#97037](https://github.com/ClickHouse/ClickHouse/pull/97037) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Update `postgres` to REL\_18\_1. [#95189](https://github.com/ClickHouse/ClickHouse/pull/95189) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Use `libexpat` 2.7.3. [#95218](https://github.com/ClickHouse/ClickHouse/pull/95218) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Use `OpenSSL` 3.5.5. [#95345](https://github.com/ClickHouse/ClickHouse/pull/95345) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Use `simdjson` v4.2.4. [#97129](https://github.com/ClickHouse/ClickHouse/pull/97129) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Use `libarchive` 3.8.5. [#97131](https://github.com/ClickHouse/ClickHouse/pull/97131) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Use `fast_float` v8.2.3. [#97133](https://github.com/ClickHouse/ClickHouse/pull/97133) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Use `abseil-cpp` 20260107.1, `s2geometry` to v0.13.1. [#97134](https://github.com/ClickHouse/ClickHouse/pull/97134) ([Konstantin Bogdanov](https://github.com/thevar1able)).
- Bump `libxml2` to 2.15.1. [#95574](https://github.com/ClickHouse/ClickHouse/pull/95574) ([Robert Schulze](https://github.com/rschu1ze)).
- Upgraded 7 Tier-3 integration test Docker images from EOL or removed base images to current supported versions. [#97314](https://github.com/ClickHouse/ClickHouse/pull/97314) ([Rahul](https://github.com/motsc)).
- Add TPC-DS benchmark queries. [#97349](https://github.com/ClickHouse/ClickHouse/pull/97349) ([Raufs Dunamalijevs](https://github.com/rienath)).
- Replace individual x86 instruction-set cmake options (`ENABLE_SSSE3`, `ENABLE_AVX2`, `NO_SSE3_OR_HIGHER`, `ARCH_NATIVE`, etc.) with a single numeric `X86_ARCH_LEVEL` option (`1`/`2`/`3`/`4`), matching the standard x86-64 microarchitecture levels already used by the runtime dispatch system. [#97354](https://github.com/ClickHouse/ClickHouse/pull/97354) ([Raúl Marín](https://github.com/Algunenano)).
- Avoid instantiating `division_by_nullable=true` template variants for non-division operations in `FunctionBinaryArithmetic`, reducing compilation time and binary size. [#97496](https://github.com/ClickHouse/ClickHouse/pull/97496) ([Raúl Marín](https://github.com/Algunenano)).
- Reduce the include footprint of `Exception.h` by removing it from high-fan-out headers like `typeid_cast.h`, `assert_cast.h`, `Context_fwd.h`, `IDataType.h`, and various Column headers. [#97497](https://github.com/ClickHouse/ClickHouse/pull/97497) ([Raúl Marín](https://github.com/Algunenano)).
- Always use bundled `compiler-rt` headers (sanitizer and XRay interfaces) instead of the host compiler's headers, and build `compiler-rt` libraries from source by default. [#97499](https://github.com/ClickHouse/ClickHouse/pull/97499) ([Raúl Marín](https://github.com/Algunenano)).
- Avoid including boost/multiprecision headers in `wide_integer_impl.h` on platforms with adequate `long double`, improving build time. [#96633](https://github.com/ClickHouse/ClickHouse/pull/96633) ([Alexey Milovidov](https://github.com/alexey-milovidov)).
- Implement LLVM Code Coverage job and enable it initially for master branch. [#90952](https://github.com/ClickHouse/ClickHouse/pull/90952) ([Alexey Bakharew](https://github.com/alexbakharew)).
- Enable fast libcxx hardening for release builds. This is mostly needed for out-of-bounds checks. Given performance tests results, no noticeable performance impact is expected. [#94757](https://github.com/ClickHouse/ClickHouse/pull/94757) ([Miсhael Stetsyuk](https://github.com/mstetsyuk)).

### ClickHouse release 26.1, 2026-01-29. [Presentation](https://presentations.clickhouse.com/2026-release-26.1/), [Video](https://www.youtube.com/watch?v=fWuYt4M0xE4)[​](#261 "Direct link to 261")

#### Backward Incompatible Change[​](#backward-incompatible-change-2 "Direct link to Backward Incompatible Change")