ClickHouse 26.10 brings a substantial set of changes to the database, including a new way to write function pipelines and performance improvements for some queries. For data teams, the useful part is not the release’s impressive bug-fix tally, but the practical changes to how SQL is written, data is handled and workloads are controlled.
ClickHouse Watch analysis
What happened
ClickHouse says version 26.10 includes 104 new features, 225 performance optimisations and 739 bug fixes. Among the user-facing changes, a function-composition operator lets developers chain functions with |, making nested expressions easier to read. The release also adds more flexible JOIN conditions and new ways to work with text and SQLite files.
For operators, ClickHouse highlights faster GROUP BY queries, disk spilling for IN subqueries and an experimental columns cache. That cache can avoid repeatedly decompressing and deserialising the same data. A new writtenrows quota counter also lets administrators limit how many rows a user writes over a time interval.
Why it matters
The changes reach beyond tidier SQL. Row-based write limits give administrators another way to control ingestion, while the performance work targets repeated or memory-hungry operations. The function pipeline is a smaller quality-of-life improvement, but one developers can see directly in their queries. That is a more useful release story than treating 104 features as 104 equal reasons to upgrade.
Our read
This looks like a meaningful database release for both developers and operators: clearer expressions, additional data-handling tools and more control over ingestion. The experimental cache is one to test against real workloads before relying on it; the rest of the release offers plenty to investigate without turning the changelog into a treasure hunt.
What to watch
- How the experimental columns cache performs on real workloads.
- Whether the new query and JOIN options improve the cases teams care about.
- How administrators use writtenrows quotas to manage ingestion.
Discussion spark: Which matters more in a database release: performance gains on real workloads, or features that make queries and operations easier to manage?
Sources and evidence
- Source update (6 November 2026, 11:45 UTC)
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