Cluster upgrades in Azure Cosmos DB for PostgreSQL

APPLIES TO: Azure Cosmos DB for PostgreSQL (powered by the Citus database extension to PostgreSQL)

The Azure Cosmos DB for PostgreSQL managed service can handle upgrades of both the PostgreSQL server, and the Citus extension. All clusters are created with the latest Citus version available for the major PostgreSQL version you select during cluster provisioning. When you select a PostgreSQL version such as PostgreSQL 15 for in-place cluster upgrade, the latest Citus version supported for selected PostgreSQL version is going to be installed.

If you need to upgrade the Citus version only, you can do so by using an in-place upgrade. For instance, you might want to upgrade Citus 11.0 to Citus 11.3 on your PostgreSQL 14 cluster without upgrading Postgres version.

Upgrade precautions

Upgrades require some downtime in the database cluster. The exact time depends on the source and destination versions of the upgrade. To prepare for the production cluster upgrade, we recommend testing the upgrade, and measure downtime during the test.

Also, upgrading a major version of Citus can introduce changes in behavior. It's best to familiarize yourself with new product features and changes to avoid surprises.

Noteworthy Citus 12 changes:

• The default rebalance strategy changed from by_shard_count to by_disk_size.
• Support for PostgreSQL 13 has been dropped as of this version.

Noteworthy Citus 11 changes:

• Table shards might disappear in your SQL client. You can control their visibility using citus.show_shards_for_app_name_prefixes.
• There are several deprecated features.

Next steps

How to perform upgrades