Question

Is there a PostgreSQL HA solution that can handle a splitbrain situation gracefully. To elaborate, the system i’m working on is expected to run in several areas with users close to the servers there and connectivity between the zones is known to be questionable. I’d like for the users to be able to continue using the system in a degraded state (without updates from disconnected zones) and for a sensible merge once they come back online.

Answer 1

If you’re prepared to live with a time delay, there should be some log shipping solutions that you could implement with a scheduled job. Basically, you send slices of the transaction log to the backup server. Here’s 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 a full implementation of Slony-I may be clunky (at least I found it that way a couple years ago, it may have drastically improved).