Re: archive_command

On Sun, 2 Oct 2005, Simon Riggs wrote:

> Probably the best idea is to backup the last WAL file for each timeline
> seen. Keep track of that, so when the current file changes you'll know
> which timeline you're on and stick to that from then on. Or more simply,
> put some notes with your program saying "if you ever use a complex
> recovery situation, make sure to clear all archive_status files for
> higher timeline ids before using this program".

Tell me if you think this is the most reasonable way to determine the in use
WAL file:

ls -rt $PGDATA/pg_xlog/ | grep -v "backup\|archive\|RECOVERY" | tail -1

> This would not be necessary had I completed my logswitch patch in time
> for 8.1 freeze, but I regret that I was unable to do that.

What's the logswitch patch going to accomplish?  Sounds interesting.

Also, I have an interesting and unrelated question...this past weekend, we had
a failure in which we had to restore from backup.  I have created a script
which makes a base backup every two weeks and we keep the last two.  Also, we
use PITR for replication, making a base backup between the primary and
secondary server every 8 hours, and running my rsynclastlog script once/minute
to keep as up to date as possible.  Now here's the problem...the servers
switched roles on Sep 21.  We switched them back a little while after that.
When I went to replay the WAL files using the Sep 15 base backup, it happily
played back the WAL files to Sep 21 and stopped.  I presume that this means
whenever the servers switch roles I need to create a fresh base backup?

Is there any possible way to replay the other WAL files after the Sep 21
switchover/switchback?  I'm going to guess this is similar to having another
timeline.

We restored from a nightly pg_dump which we have kept doing, but that means we
lost about 20 hrs of data. :-(

--
Jeff Frost, Owner     <jeff@frostconsultingllc.com>
Frost Consulting, LLC     http://www.frostconsultingllc.com/
Phone: 650-780-7908    FAX: 650-649-1954