On Oct 5, 2005, at 8:23 AM, Ian Westmacott wrote:

Can anyone tell me what precisely a WAL buffer contains,
so that I can compute an appropriate setting for
wal_buffers (in 8.0.3)?

I know the documentation suggests there is little
evidence that supports increasing wal_buffers, but we
are inserting a large amount of data that, I believe,
easily exceeds the default 64K in a single transaction.
We are also very sensitive to write latency.

As background, we are doing a sustained insert of 2.2
billion rows in 1.3 million transactions per day.  Thats
about 1700 rows per transaction, at (roughly) 50 bytes
per row.


The WAL Configuration chapter (25.2) has a pretty good discussion of how wal_buffers is used:


You might also take a look at Josh Berkus' recent testing on this setting:


Thomas F. O'Connell
Co-Founder, Information Architect
Sitening, LLC

Strategic Open Source: Open Your i™

110 30th Avenue North, Suite 6
Nashville, TN 37203-6320
615-469-5151 (fax)

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