| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Teran <david(dot)teran(at)cluster9(dot)com> |
| Cc: | Shridhar Daithankar <shridhar_daithankar(at)myrealbox(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: optimizing Postgres queries |
| Date: | 2004-01-05 18:52:40 |
| Message-ID: | 16230.1073328760@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
David Teran <david(dot)teran(at)cluster9(dot)com> writes:
> What we found out now is that a query with a single 'where' works fine,
> the query planer uses the index but when we have 'two' where clauses it
> does not use the index anymore:
> EXPLAIN ANALYZE SELECT columns... FROM "KEY_VALUE_META_DATA" t0 WHERE
> (t0."ID_VALUE" = 14542); performs fine, less than one millisecond.
> EXPLAIN ANALYZE SELECT columns... FROM "KEY_VALUE_META_DATA" t0 WHERE
> (t0."ID_VALUE" = 14542 OR t0."ID_VALUE" = 14550); performs bad: about
> 235 milliseconds.
Please, when you ask this sort of question, show the EXPLAIN ANALYZE
output. It is not a virtue to provide minimal information and see if
anyone can guess what's happening.
regards, tom lane
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