| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Hunter Hillegas <lists(at)lastonepicked(dot)com> |
| Cc: | Dann Corbit <DCorbit(at)connx(dot)com>, Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>, PostgreSQL <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Left Join Not Using Index? |
| Date: | 2003-04-23 05:30:05 |
| Message-ID: | 24304.1051075805@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Hunter Hillegas <lists(at)lastonepicked(dot)com> writes:
> Can anyone point me in another direction to optimize this
AFAICS you cannot improve that without changing the query structure
and/or the database layout. Because the WHERE clause is a bunch of OR'd
conditions, it's useless for restricting either individual table scan
making up the join --- there is really no implementation short of
forming the entire join described by the FROM ... JOIN ... ON ... part
of the query and then testing each individual row against the WHERE
clause. While that is the abstract semantic model implied by the SQL
spec, it's not exactly how you want a query to really be done :-(.
regards, tom lane
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