Introduction
Step 1: Set up a standby cluster
- Clone your existing ClickHouse cluster to create a standby cluster.
- Set up replication between the existing and the standby clusters to ensure that the data is up-to-date.
Step 2: Upgrade ClickHouse on the standby cluster
- Follow the standard upgrade process for ClickHouse on the standby cluster.
- Ensure that the upgrade is successful and there are no issues.
Step 3: Test the upgraded standby cluster
- Run tests on the upgraded standby cluster to ensure that everything is functioning correctly.
- Monitor the standby cluster to ensure that there are no issues.
Step 4: Switch traffic to the standby cluster
- Update the DNS records or load balancer settings to route traffic to the upgraded standby cluster.
- Ensure that traffic is flowing to the standby cluster.
Step 5: Upgrade ClickHouse on the main cluster
- Follow the standard upgrade process for ClickHouse on the main cluster.
- Ensure that the upgrade is successful and there are no issues.
Step 6: Test the upgraded main cluster
- Run tests on the upgraded main cluster to ensure that everything is functioning correctly.
- Monitor the main cluster to ensure that there are no issues.
Step 7: Switch traffic back to the main cluster
- Update the DNS records or load balancer settings to route traffic back to the main cluster.
- Ensure that traffic is flowing to the main cluster.
Step 8: Monitor the system
- Monitor the ClickHouse system to ensure that there are no issues after the upgrade process.
- Identify and resolve any problems as soon as possible to minimize downtime.
Step 9: Rollback plan
- Have a rollback plan in place in case any issues occur during the upgrade process.
- Test the rollback plan to ensure that it works as expected.
Conclusion
By following the above steps, you can implement zero downtime ClickHouse upgrades. It’s essential to test and monitor the system at every step to ensure that there are no issues and to take corrective actions if any problems arise.
To read more articles on ClickHouse internals, do consider reading the below articles
