Maintenance in Managed Service for PostgreSQL
In Managed Service for PostgreSQL, maintenance means:
- Automatic installation of DBMS updates and revisions for hosts (including disabled clusters).
- Changes to the host class and storage size.
- Other maintenance activities.
Changing a major DBMS version is not part of maintenance. For more information about major version changes, see PostgreSQL version upgrade.
Maintenance window
You can set the preferred maintenance time when creating a cluster or updating its settings:
- The arbitrary option (default) allows performing maintenance at any time.
- The by schedule option allows setting the preferred maintenance start day and time (UTC). For example, you can choose a time when the cluster is least loaded.
Maintenance procedure
In Managed Service for PostgreSQL single-host clusters, a master host undergoes maintenance. Therefore, it may become unavailable in case it is restarted.
In multi-host clusters, the maintenance is run as follows:
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Replica hosts undergo maintenance one by one. Their queue positions are random. A replica becomes temporarily unavailable if it needs to be restarted during maintenance.
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Master host undergoes maintenance and gets updated. If it is restarted and becomes unavailable, one of the replicas takes its role.
If you access a cluster using the FQDN of the master host, the cluster may become unavailable. To make your application continuously available, access the cluster using a special FQDN that always points to the master host.