On Tue, 2008-10-28 at 23:45 -0400, Robert Haas wrote:
> One concern that I have about this approach is that the situation in
> which people are probably most concerned about COPY performance is
> restoring a dump. In that case, the COPY will be the only thing
> running, and using a BufferAccessStrategy is an anti-optimization. I
> don't think it's a very big effect (any testing anyone can do on real
> hardware rather than what I have would be appreciated) but I'm sort of
> unsold of optimizing for what I believe to be the less-common use
> case. If the consensus is to reverse course on this point I'm happy
> to rip those changes back out and resubmit; they are a relatively
> small proportion of the patch.
Having COPY use a BAS is mainly to ensure it doesn't swamp the cache.
Which is a gain in itself.
If you say its a loss you should publish timings to support that. Using
a BAS for VACUUM was a performance gain, not a loss.
-- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support