| From: | Mike Mascari <mascarm(at)mascari(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Fuzzy cost comparison to eliminate redundant planning |
| Date: | 2004-03-28 22:07:41 |
| Message-ID: | 40674CAD.4000702@mascari.com |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> I've been looking at the planner performance problem exhibited by
> Eric Brown:
> http://archives.postgresql.org/pgsql-performance/2004-03/msg00273.php
>
> While a nine-way join is inherently going to take some time to plan
> (if you don't constrain the search space with JOIN), it seemed to me
> that this particular query was taking even longer than I'd expect.
...
> I found that this reduced the planning time of Eric's
> query by about 40%, without changing the resulting plan.
More great news, as always. IIRC you recently bumped the default
GEQO threshold from eleven to twelve. With your new fuzzy comparison
patch is twelve still the appropriate number? Or does the fuzzy
comparison scale all planning time down and therefore the default
threshold should remain where it is?
Mike Mascari
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