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Re: BufferAccessStrategy for bulk insert

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Postgres Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: BufferAccessStrategy for bulk insert
Date: 2008-10-29 21:03:14
Message-ID: 1225314194.3971.305.camel@ebony.2ndQuadrant (view raw or flat)
Thread:
Lists: pgsql-hackers
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.com
 PostgreSQL Training, Services and Support


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