Re: Trimming transaction logs after extended WAL archive failures

On Tue, Mar 25, 2014 at 6:33 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> 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.
>

Actually my description is rather garbled, mixing up what I saw
when wal_keep_segments was lowered, not when recovering from a long lasting
archive failure. Nevertheless, checkpoints are what provoke the removal of
excessive WAL files. Are you logging checkpoints? What do they say?
Also, what is in pg_xlog/archive_status ?

Cheers,

Jeff