Is is possible to persuade the query planner that ~* operations are grossly expensive?
От | Nick Howden |
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Тема | Is is possible to persuade the query planner that ~* operations are grossly expensive? |
Дата | |
Msg-id | 20021217092705.9AC8F476281@postgresql.org обсуждение исходный текст |
Ответы |
Re: Is is possible to persuade the query planner that ~* operations are grossly expensive?
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Список | pgsql-admin |
Is is possible to persuade the query planner that ~* operations are grossly expensive - or at least much more expensive than some other operations. My reason is that I have a databsase on which we do a lot of queries of the form SELECT * FROM primary_table secondary_table as t1 secondary_table as t2 WHERE primary_table.id = t1.id AND primary_table.id = t2.id AND t1.col1 = 1 AND t2.col1 = 2 AND primary_table.blob ~* 'wibble'; unfortunately the query optimiser always tries to do the ~* operator before it has done the other (more selective) queries, and over 100,000+ rows this is very slow. So, can I force the query optimizer to delay doing the ~* until after the selective joins? -- Nick Howden - Senior IT Analyst QinetiQ Trusted Information Management Woodward Building, Room B009 Malvern Technology Park, WR14 3PS Telephone 01684 895566, Fax 896660 The Information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful
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