Re: add_path optimization

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Robert Haas" <robertmhaas(at)gmail(dot)com>, <Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: add_path optimization
Date: 2009-02-03 16:27:27
Message-ID: 49881C0F.EE98.0025.0@wicourts.gov
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>>> Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I had a suspicion we were going to see something like this. You're
> using several NOT EXISTS clauses and 8.4devel is converting those
into
> Anti Joins. Aside from the longer planning time, the resulting plan
> appears to have a much higher estimated cost, so I'm suspicious of a
> bug in the new Semi/Anti join stuff, but I don't have time to track
it
> down right now (and I suspect Tom will figure it out faster than I
can
> anyway).

The 8.4 plan also don't seem to run as fast. Attached is EXPLAIN
ANALYZE output from the 8.3.5 database I dumped from for my 8.4devel
tests. I tried the same run on 8.4devel and it is still running after
20 minutes. I will let it cook for a while.

-Kevin

Attachment Content-Type Size
explain-analyze-8.3.5.txt text/plain 14.2 KB

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