James Sewell wrote:
> My understanding is that WAL archiving can not be enabled on the slave in a streaming replication
> pair.
It can be enabled. Did you try it?
> If this is correct, is there a reason behind it? I can see logs showing up in pg_xlog, so could they
> not be archived?
These are files containing the WAL data replicated from the master.
They won't be archived.
> The reason I ask is if this happened it would allow the following with a streaming replication pair
> (A,B):
>
>
> 1. Start A as master
> 2. Attach B as slave using basebackup
> 3. work ....
> 4. Promote B to master
>
> 5. Restore A from a scheduled backup to a time before promotion
> 6. Attach A as slave pointing at B's WAL archive
>
> If we used A's WAL archive in this case and A had writes after the promotion then we would get
> timeline errors.
You shouldn't with 9.3, because in that case A would follow the
timeline switch introduced by B's promotion rather than its old timelime.
http://www.postgresql.org/message-id/E1TjCRc-00084r-1H@gemulon.postgresql.org
I may be missing something there since I have never tried it.
> As far as I can tell, using the WAL archive from B would resolve this issue.
That should work in any event.
Yours,
Laurenz Albe