Upgrading Amazon Aurora PostgreSQL DB clusters
Amazon Aurora makes new versions of the PostgreSQL database engine available in AWS Regions only after extensive testing. You can upgrade your Aurora PostgreSQL DB clusters to the new version when it's available in your Region.
Depending on the version of Aurora PostgreSQL that your DB cluster is currently running, an upgrade to the new release is either a minor upgrade or a major upgrade. For example, upgrading an Aurora PostgreSQL 11.15 DB cluster to Aurora PostgreSQL 13.6 is a major version upgrade. Upgrading an Aurora PostgreSQL 13.3 DB cluster to Aurora PostgreSQL 13.7 is a minor version upgrade. In the following topics, you can find information about how to perform both types of upgrades.
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Overview of the Aurora PostgreSQL upgrade processes
The differences between major and minor version upgrades are as follows:
- Minor version upgrades and patches
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Minor version upgrades and patches include only those changes that are backward-compatible with existing applications. Minor version upgrades and patches become available to you only after Aurora PostgreSQL tests and approves them.
Minor version upgrades can be applied for you automatically by Aurora. When you create a new Aurora PostgreSQL DB cluster, the Enable minor version upgrade option is preselected. Unless you turn off this option, minor version upgrades are applied automatically during your scheduled maintenance window. For more information about the automatic minor version upgrade (AmVU) option and how to modify your Aurora DB cluster to use it, see Automatic minor version upgrades for Aurora DB clusters.
If the automatic minor version upgrade option isn't set for your Aurora PostgreSQL DB cluster, your Aurora PostgreSQL isn't automatically upgraded to the new minor version. Instead, when a new minor version is released in your AWS Region and your Aurora PostgreSQL DB cluster is running an older minor version, Aurora prompts you to upgrade. It does so by adding a recommendation to the maintenance tasks for your cluster.
Patches aren't considered an upgrade, and they aren't applied automatically. Aurora PostgreSQL prompts you to apply any patches by adding a recommendation to maintenance tasks for your Aurora PostgreSQL DB cluster. For more information, see How to perform minor version upgrades and apply patches.
Note
Patches that resolve security or other critical issues are also added as maintenance tasks. However, these patches are required. Make sure to apply security patches to your Aurora PostgreSQL DB cluster when they become available in your pending maintenance tasks.
The upgrade process involves the possibility of brief outages as each instance in the cluster is upgraded to the new version. However, after Aurora PostgreSQL versions 14.3.3, 13.7.3, 12.11.3, 11.16.3, 10.21.3 and other higher releases of these minor versions and newer major versions, the upgrade process uses the zero-downtime patching (ZDP) feature. This feature minimizes outages, and in most cases completely eliminates them. For more information, see Minor release upgrades and zero-downtime patching.
Note
ZDP isn't supported in the following cases:
When Aurora PostgreSQL DB clusters are configured as Aurora Serverless v1.
When Aurora PostgreSQL DB clusters are configured as Aurora global database in the secondary AWS Regions.
During the upgrade of reader instances in Aurora global database.
During OS patches and OS upgrades.
ZDP is supported for Aurora PostgreSQL DB clusters that are configured as Aurora Serverless v2.
- Major version upgrades
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Unlike for minor version upgrades and patches, Aurora PostgreSQL doesn't have an automatic major version upgrade option. New major PostgreSQL versions might contain database changes that aren't backward-compatible with existing applications. The new functionality can cause your existing applications to stop working correctly.
To prevent any issues, we strongly recommend that you follow the process outlined in Testing an upgrade of your production DB cluster to a new major version before upgrading the DB instances in your Aurora PostgreSQL DB clusters. First ensure that your applications can run on the new version by following that procedure. Then you can manually upgrade your Aurora PostgreSQL DB cluster to the new version.
The upgrade process involves the possibility of brief outage when all the instances in the cluster are upgraded to the new version. The preliminary planning process also takes time. We recommend that you always perform upgrade tasks during your cluster's maintenance window or when operations are minimal. For more information, see Performing a major version upgrade.
Note
Both minor version upgrades and major version upgrades might involve brief outages. For that reason, we recommend strongly that you perform or schedule upgrades during your maintenance window or during other periods of low utilization.
Aurora PostgreSQL DB clusters occasionally require operating system updates. These updates might include a newer version of glibc library. During such updates, we recommend you to follow the guidelines as described in Collations supported in Aurora PostgreSQL.
Alternative blue/green upgrade technique
In some situations, your top priority is to perform an immediate switchover from the old cluster to an upgraded one. In such situations, you can use a multistep process that runs the old and new clusters side-by-side. Here, you replicate data from the old cluster to the new one until you are ready for the new cluster to take over. For details, see Using Amazon RDS Blue/Green Deployments for database updates.
