On 02/22/2013 11:55 PM, jeff@pgexperts.com wrote:
>
> While doing acceptance testing on a new Ubuntu 12.04 PostgreSQL server
> running 9.2.3, we set checkpoint_segments = 128,
> checkpoint_completion_target = 0.9 and placed pg_xlog on a separate 20G
> partition. Also, archive_mode = off on this system.
>
> According to the docs, you would expect the system to attempt to keep the
> WAL files down close to 3 * checkpoint_segments + 1. Unfortunately, this
> does not appear to be the case because a pgbench run would run the pg_xlog
> partition out of space.
>
[................]
Hello Jeff
We reported this back in 2011, but we did not get to any conclusion:
http://www.postgresql.org/message-id/4DE89072.7070305@usit.uio.no
In our case, we had this problem when creating a GIN index.
I think the problem has something to do with checkpoints, I think the
number of WAL files will grow beyond the limit defined because the
system can not be finish with checkpoints. A good start to try to
explain what it is happening would be to try to identify or describe the
situations where checkpoints can take very long to complete or fail
altogether.
We are interested in this subject because we have had this problem a few
times. But we have not been able to identify the reason that triggers this.
regards,
--
Rafael Martinez Guerrero
Center for Information Technology
University of Oslo, Norway
PGP Public Key: http://folk.uio.no/rafael/