How to upgrade Postgresql 8.3.x to 8.4.x without downtime?

Question

Is it possible to upgrade from PostgreSQL 8.3.x to 8.4.x without downtime? We have a warm standby configuration with WAL shipping so we have the option upgrade the standby first, but WAL shipping does not apparently work from a 8.3.x primary to a 8.4.x slave or vice versa. Any suggestions would be appreciated as we have a mission critical app.

Answer 1

A dump/restore using pg_dump is required for those wishing to migrate data from any previous release.

http://www.postgresql.org/docs/8.4/static/release-8-4.html

In general, log shipping between servers running different major PostgreSQL release levels will not be possible.

http://www.postgresql.org/docs/8.3/static/warm-standby.html

The only other option I see is http://wiki.postgresql.org/wiki/In-place_upgrade which links to: http://pgfoundry.org/projects/pg-migrator/

Other than that, I imagine you could put the database in read-only mode and perform the upgrade on the standby or another server.

I hope you well-tested this critical app on 8.4 already :)