| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Gregory Stark <stark(at)enterprisedb(dot)com> |
| Cc: | "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>, "Mouhamadou Dia" <MDia(at)accovia(dot)com>, pgsql-bugs(at)postgresql(dot)org |
| Subject: | Re: RE : RE : BUG #3519: Postgres takes the wrong query plan resulting in performance issues |
| Date: | 2007-08-07 01:30:53 |
| Message-ID: | 6999.1186450253@sss.pgh.pa.us |
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| Lists: | pgsql-bugs |
Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> The structure of your query is a whole series of left outer joins, the result
> of which is then (inner) joined with one more table. The outer joins return a
> whole lot of records but the inner join is only going to match a few of them.
Hmmm ... actually I see 6 tables inside the join-tree and four more
loose in the FROM-clause, ten relations altogether. Which means the OP
is falling foul of from_collapse_limit, and it's not investigating every
possible join order. Try setting from_collapse_limit to more than 10.
regards, tom lane
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