Re: [PERFORM] [HACKERS] More benchmarking of wal_buffers

From: Kevin Brown <kevin(at)sysexperts(dot)com>
To: Hackers <pgsql-hackers(at)postgresql(dot)org>, pgsql-performance(at)postgresql(dot)org, Advocacy <pgsql-advocacy(at)postgresql(dot)org>
Subject: Re: [PERFORM] [HACKERS] More benchmarking of wal_buffers
Date: 2003-02-14 03:46:46
Message-ID: 20030214034646.GA1847@filer
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Tom Lane wrote:
> "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au> writes:
> > I've just spent the last day and a half trying to benchmark our new database
> > installation to find a good value for wal_buffers. The quick answer - there
> > isn't, just leave it on the default of 8.
>
> I don't think this is based on a useful test for wal_buffers. The
> wal_buffers setting only has to be large enough for the maximum amount
> of WAL log data that your system emits between commits, because a commit
> (from anyone) is going to flush the WAL data to disk (for everyone).

What happens when the only transaction running emits more WAL log data
than wal_buffers can handle? A flush happens when the WAL buffers
fill up (that's what I'd expect)? Didn't find much in the
documentation about it...

--
Kevin Brown kevin(at)sysexperts(dot)com

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