Re: optimizing Postgres queries - Mailing list pgsql-performance

From Tom Lane
Subject Re: optimizing Postgres queries
Date
Msg-id 16230.1073328760@sss.pgh.pa.us
Whole thread Raw
In response to Re: optimizing Postgres queries  (David Teran <david.teran@cluster9.com>)
Responses Re: optimizing Postgres queries  (David Teran <david.teran@cluster9.com>)
List pgsql-performance
David Teran <david.teran@cluster9.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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