Re: auto-sizing wal_buffers - Mailing list pgsql-hackers

From Fujii Masao
Subject Re: auto-sizing wal_buffers
Date
Msg-id AANLkTi=Dgn-3jRj+QUMCunMgicwifZENHXKnKMuTQWA5@mail.gmail.com
Whole thread Raw
In response to Re: auto-sizing wal_buffers  (Josh Berkus <josh@agliodbs.com>)
List pgsql-hackers
On Sun, Jan 16, 2011 at 7:34 AM, Josh Berkus <josh@agliodbs.com> wrote:
> I think we can be more specific on that last sentence; is there even any
> *theoretical* benefit to settings above 16MB, the size of a WAL segment?
>  Certainly there have been no test results to show any.

If the workload generates 16MB or more WAL for wal_writer_delay,
16MB or more of wal_buffers would be effective. In that case,
wal_buffers is likely to be filled up with unwritten WAL, then you have
to write buffers while holding WALInsert lock. This is obviously not
good.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center


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