On 1/14/11 10:51 PM, Greg Smith wrote:
>
> ! Since the data is written out to disk at every transaction
> commit,
> ! the setting many only need to be be large enough to hold the
> amount
> ! of WAL data generated by one typical transaction. Larger values,
> ! typically at least a few megabytes, can improve write performance
> ! on a busy server where many clients are committing at once.
> ! Extremely large settings are unlikely to provide additional
> benefit.
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
showany.
If we don't know, keep it vague, but otherwise I suggest:
"Settings larger than the size of a single WAL segment (16MB by default)
are unlikely to produce any benefit."
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com
