Re: Trimming transaction logs after extended WAL archive failures

On Tuesday, March 25, 2014, Steven Schlansker <steven(at)likeness(dot)com> wrote:

> Hi everyone,
>
> I have a Postgres 9.3.3 database machine. Due to some intelligent work on
> the part of someone who shall remain nameless, the WAL archive command
> included a '> /dev/null 2>&1' which masked archive failures until the disk
> entirely filled with 400GB of pg_xlog entries.
>

PostgreSQL itself should be logging failures to the server log, regardless
of whether those failures log themselves.

> I have fixed the archive command and can see WAL segments being shipped
> off of the server, however the xlog remains at a stable size and is not
> shrinking. In fact, it's still growing at a (much slower) rate.
>

The leading edge of the log files should be archived as soon as they fill
up, and recycled/deleted two checkpoints later. The trailing edge should
be archived upon checkpoints and then recycled or deleted. I think there
is a throttle on how many off the trailing edge are archived each
checkpoint. So issues a bunch of "CHECKPOINT;" commands for a while and
see if that clears it up.

Cheers,

Jeff