PostgreSQL Availability and Merge

Question

Is there a PostgreSQL HA solution that can handle the splitbrain situation gracefully. To develop, the system I'm working on is expected to work in several areas with users located next to the servers, and the connection between these zones is known to be in doubt. I would like to allow users to continue to use the system in a degraded state (without updates from disconnected zones) and for a reasonable merger after they return to the network.

Answer 1

If you are willing to live with a time delay, there should be some log shipping solutions that you could implement with the scheduled task. Basically, you send transaction log fragments to the backup server. Here are some links with a better description:

• http://developer.postgresql.org/pgdocs/postgres/warm-standby.html
• http://developer.postgresql.org/~wieck/slony1/adminguide-1.1.rc1/logshipping.html
• http://www.network-theory.co.uk/docs/postgresql/vol3/RecordbasedLogShipping.html

Note that the full implementation of Slony-I can be awkward (at least I found it that way a couple of years ago, maybe it has improved significantly).