// ClickHouse support
ClickHouse moves fast. Your cluster does not have to.
Patched builds for the release you run, and a clean move off ZooKeeper.
ClickHouse ships a stable release roughly every month and supports only the three latest, plus LTS releases for a year. As of September 2026 its security policy lists 26.9, 26.8, 26.7 and 26.3 as supported, and every 25.x release and older as unsupported. Many replicated clusters also still coordinate through an Apache ZooKeeper ensemble. OSSeva ships patched, signed ClickHouse builds for the release you run, migrates the coordination layer to ClickHouse Keeper, and runs the cluster around the clock if you want it to.
Trusted globally by enterprises
Why ClickHouse clusters fall out of support
The release train is the feature. It is also why a cluster that was current last year is unsupported now.
The support window is months, not years
The ClickHouse documentation says stable releases ship roughly monthly and the three latest are supported with backported fixes. LTS releases come twice a year and are supported for one year. A cluster pinned to one release for stability ages out of security fixes within a year at most.
Upgrades touch behaviour, not just binaries
Each release can change settings defaults, query behaviour and storage internals. Teams with large schemas, materialised views and downstream dashboards test every upgrade, and that testing is what makes them slip behind.
The coordination layer is often older still
Replicated tables need ZooKeeper 3.4.5 or newer, or ClickHouse Keeper, which the documentation recommends. Clusters built before Keeper matured usually run a ZooKeeper ensemble, and those ensembles are often on 3.4 to 3.7, lines the ZooKeeper project no longer patches.
The dates that matter
2020-06-01
ZooKeeper 3.4 reaches end of life. Many early replicated ClickHouse clusters coordinate through 3.4.
2021-12
ClickHouse 21.12 declares clickhouse-keeper feature complete.
2022-05
ClickHouse Keeper in production in ClickHouse Cloud.
2024-02-02
ZooKeeper 3.7, the last line before 3.8, reaches end of life.
2026-09-16
Five new ZooKeeper advisories, assessed by the project only against 3.8 and 3.9.
2026-09
ClickHouse's security policy supports 26.9, 26.8, 26.7 and 26.3. Every 25.x release and older is unsupported.
What OSSeva delivers
Patched ClickHouse builds
Security fixes backported to the ClickHouse release you run, built from upstream source and shipped as signed packages and container images. Settings, formats and query behaviour stay as they are, so the upgrade you were avoiding stays optional.
ZooKeeper to ClickHouse Keeper migration
A tested move from your ZooKeeper ensemble to ClickHouse Keeper. Keeper speaks the ZooKeeper client protocol, but its storage and interserver formats differ, so the two cannot share an ensemble. We convert the data with clickhouse-keeper-converter, rehearse the cutover, and patch the old ensemble until it is retired.
24/7 ClickHouse operations
Monitoring of replication queues, merges, parts counts and Keeper quorum, a 15-minute P1 response, named engineers, and upgrade execution when you decide to move.
Your options, compared
| Option | What you get | Trade-off |
|---|---|---|
| Upgrade every month | Community fixes on a supported release | A test cycle for every release, indefinitely. |
| Stay on LTS | Two upgrades a year instead of twelve | Each LTS is supported for one year, so a missed upgrade still leaves you exposed. |
| Managed ClickHouse service | The vendor runs the cluster and the upgrades | A platform migration, with data and access moving to the provider's environment. |
| OSSeva support | Patched builds for your release, Keeper migration and 24/7 operations | A subscription per cluster. |
Supported ClickHouse releases from SECURITY.md in the ClickHouse GitHub repository. Release cadence from the ClickHouse production FAQ. Keeper facts from the ClickHouse Keeper and replication documentation and the 2021 changelog. ZooKeeper dates from zookeeper.apache.org.
Frequently asked questions
Which ClickHouse versions are still supported?
As of September 2026, ClickHouse's security policy lists 26.9, 26.8, 26.7 and 26.3 as supported with security updates. Every 25.x release and older, and 26.1, 26.2, 26.4, 26.5 and 26.6, are listed as unsupported.
How long is a ClickHouse LTS release supported?
One year from its first release, according to the ClickHouse documentation. LTS releases ship twice a year, and stable releases roughly monthly with the three latest supported.
Can ClickHouse run without ZooKeeper?
Yes. ClickHouse Keeper is a Raft-based replacement that speaks the ZooKeeper client protocol, and the replication documentation recommends it over ZooKeeper.
Can ZooKeeper and ClickHouse Keeper run in one ensemble?
No. Keeper's snapshot, log and interserver formats differ from ZooKeeper's, so an ensemble is one or the other. Existing data moves across with clickhouse-keeper-converter during a planned cutover.
Do you patch the ZooKeeper under ClickHouse too?
Yes. OSSeva ships patched builds for ZooKeeper 3.4, 3.5, 3.6 and 3.7, so the ensemble stays covered while the migration to Keeper runs, or for as long as it also serves other systems.
Keep ClickHouse patched without upgrading every month.
Talk to an engineer about your release, your coordination layer and your upgrade plan.