On 16/01/2004, at 2:44 AM, Tom Lane wrote: ...
As noted elsewhere, it's highly likely that this has nothing to do with
the OS, and everything to do with write caching in the disks being used.

I assume you are benchmarking small individual transactions (one insert
per xact). In such scenarios it's essentially impossible to commit more
than one transaction per revolution of the WAL disk, because you have to
write the same WAL disk page repeatedly and wait for it to get down to
the platter. When you get results that are markedly in excess of the
disk RPM figure, it's proof positive that the disk is lying about write
complete (or that you don't have fsync on).

Tom, thanks for this explanation - we'll check this out straight away, but it would explain a lot.

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