Re: wal_buffer tests in

From: "Zeugswetter Andreas DAZ SD" <ZeugswetterA(at)spardat(dot)at>
To: <josh(at)agliodbs(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: wal_buffer tests in
Date: 2005-07-28 09:05:25
Message-ID: E1539E0ED7043848906A8FF995BDA579517A52@m0143.s-mxs.net
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> I ran a wal_buffer test series. It appears that increasing the
> wal_buffers is indeed very important for OLTP applications,
> potentially resulting in as much as a 15% average increase in
> transaction processing.
> What's interesting is that this is not just true for 8.1, it's true
for
> 8.0.3 as well.

You will want the log write to write up to at least 256kb (>= 256kb you
reach
the max Mb/s a disk can write) (if that is possible, no commit/fsync
inbetween).
You will also want enough buffers, that can be filled while the 256kb
are written.
Thus a value of at least 64 with 8k pages seems reasonable.

Andreas

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