Re: Trimming transaction logs after extended WAL archive failures - Mailing list pgsql-general

From Jeff Janes
Subject Re: Trimming transaction logs after extended WAL archive failures
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Msg-id CAMkU=1zGRYG_LxryPbMnZZctDXPAjHJjZ0Xf7PZg8BV6rMSbtw@mail.gmail.com
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In response to Re: Trimming transaction logs after extended WAL archive failures  (Jeff Janes <jeff.janes@gmail.com>)
Responses Re: Trimming transaction logs after extended WAL archive failures  (Steven Schlansker <steven@likeness.com>)
List pgsql-general
On Tue, Mar 25, 2014 at 6:33 PM, Jeff Janes <jeff.janes@gmail.com> wrote:
On Tuesday, March 25, 2014, Steven Schlansker <steven@likeness.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

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