PostgreSQL: minor update or major upgrade?

The PostgreSQL docs draw a sharp line. Minor releases never change the internal storage format. You replace the executables while the server is down, restart, and the data directory stays as it was.

With a major release the storage format may change. The traditional route is dump and restore, which can be slow. pg_upgrade is the faster method, and replication methods exist too.

Move	Example	Data
Minor	10.0 to 10.6	Directory unchanged
Major	Next major version	Dump and restore, pg_upgrade or replication

Example

Illustrative. 2 clusters, a Saturday window of 4 hours. A minor update fits easily with both. A major upgrade gets one cluster per window, after a staging rehearsal that gives you a measured time.

Important

New major versions typically bring user-visible incompatibilities, so application changes may be needed. Read the release notes. Packaged versions may ship their own upgrade scripts, so check that documentation first.

Plan the window

• ☐ Compare major numbers, not only the full version
• ☐ Pick a method for each major upgrade
• ☐ Time a rehearsal on staging
• ☐ Read the release notes for changes

Gantt chart — tasks, owners, dates →

Source: postgresql.org, Documentation, Upgrading a PostgreSQL Cluster.