Re: can we avoid pg_basebackup on planned switches?

Anybody?

On Jul 27, 2012, at 10:00 AM, Ben Chobot wrote:

> We make heavy use of streaming replication on PG 9.1 and it's been great for us. We do have one issue with it, though, and that's when we switch master nodes - currently, the documentation says that you must run pg_basebackup on your old master to turn it into a slave. That makes sense when the old master had crashed, but it seems that in the case of a planned switch, we could do better. Here's what we tried that seemed to work... are we shooting ourselves in the foot?
>
> 1. Cleanly shut down the current master.
> 2. Pick a slave, turn it into the new master.
> 3. Copy the new pg_xlog history file over to the old master.
> 4. On any other slaves (many of our clusters are 3 nodes), we already have "recovery_target_timeline=latest" and wal archiving, so they should already be working as slaves of the new master.
> 5. Set up recovery.conf on the old master to be like the other slaves.
> 6. Start up the old master.
>
> Have we just avoided running pg_basebackup, or have we just given ourselves data corruption? Because we're using wal archiving, can we simplify and leave out step 3?