Re: Another try at reducing repeated detoast work for PostGIS

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Another try at reducing repeated detoast work for PostGIS
Date: 2009-08-17 18:29:18
Message-ID: 1250533758.16514.12.camel@monkey-cat.sm.truviso.com
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On Mon, 2009-08-17 at 13:37 -0400, Tom Lane wrote:
> Thinking about it again, it seems to me that a much narrower patch
> could solve the specific forms of the problem that the PostGIS folk
> are seeing. Instead of trying to have a general-purpose method of
> preventing repeat de-toasting, we could just prevent it for inner
> indexscans by having ExecIndexEvalRuntimeKeys() detoast anything it's
> passing to the index AM.

With this patch, are there still situations where we should be concerned
about repeated de-toasting, or does this solve the biggest part of the
problem?

If so, is it possible that two similar plans for the same query might
perform differently due to repeated de-toasting?

Regards,
Jeff Davis

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