Re: add_path optimization - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: add_path optimization
Date
Msg-id 49881C0F.EE98.0025.0@wicourts.gov
Whole thread Raw
In response to Re: add_path optimization  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: add_path optimization
Re: add_path optimization
List pgsql-hackers
>>> Robert Haas <robertmhaas@gmail.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


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