Re: Another try at reducing repeated detoast work for PostGIS

Jeff Davis <pgsql@j-davis.com> writes:
> 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?

Well, it solves the case people have actually complained about (twice
now).  I originally attempted to solve a larger set of cases, but it's
not clear there's enough value in that.

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

Hard to answer that one.  What's "similar"?
        regards, tom lane