Re: [WIP] Double-write with Fast Checksums

On Wed, Jan 11, 2012 at 9:47 AM, Aidan Van Dyk <aidan@highrise.ca> wrote:
> It does this by moving the FPW/IO penalty from the commit time of a
> backend dirtying the buffer first, to the eviction time of a backend
> evicting a dirty buffer.  And if you're lucky enough that the
> background writer is the only one writing dirty buffers, you'll see
> lots of improvements in your performance (equivilent of running with
> current FPW off).  But I have a feeling that many of us see backends
> having to write dirty buffers often enough too that the reduction in
> commit/WAL latency will be offset (hopefully not as much) by increased
> query processing time as backends double-write dirty buffers.

I have that feeling, too.  Someone needs to devote some time to
performance testing this stuff.

--
Robert Haas
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