Update itself is simple: update packages, restart clickhouse-server service afterwards.
- Check if the version you want to upgrade to is stable. We highly recommend the Altinity ClickHouse Stable Releases.
- Review the changelog to ensure that no configuration changes are needed.
- Update staging and test to verify all systems are working.
- Prepare and test downgrade procedures so the server can be returned to the previous version if necessary.
- Start with a “canary” update. This is one replica with one shard that is upgraded to make sure that the procedure works.
- Test and verify that everything works properly. Check for any errors in the log files.
- If everything is working well, update the rest of the cluster.
For small clusters, the BlueGreenDeployment technique is also a good option.
Last modified 2021.08.12: General corrections and updates. (876b7b6)