I've just noticed that on PostgreSQL 9.3 I can do the following with a master node A and a slave node B (as long as I have set recovery_target_timeline = 'latest'):
Stop Node A
Promote Node B
Attach Node A as slave
This is sufficient for my needs (I know it doesn't cover a crash), can anyone see any potential problems with this approach?
Yes, node A could get ahead of the point where WAL forked when promoting B. In this case you cannot reconnect A to B, and need to actually recreate a node from a fresh base backup, or rewind it. pg_rewind targets the latter, postgres core is able to to the former, and depending on things like your environment and/or the size of your server, you might prefer one or the other.
