Re: Optimizing NOT IN plans / verify rewrite
От | Maciek Sakrejda |
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Тема | Re: Optimizing NOT IN plans / verify rewrite |
Дата | |
Msg-id | AANLkTi=a2ZprXAio2dNMbbWXMLc9QeKV_QO0qcF9qesX@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Optimizing NOT IN plans / verify rewrite (Andres Freund <andres@anarazel.de>) |
Ответы |
Re: Optimizing NOT IN plans / verify rewrite
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Список | pgsql-performance |
>> All fields involved are declared NOT NULL, but thanks for the heads up. >Afair the planner doesnt use that atm. I was referring to not having to care about the strange NULL semantics (as per your original comment), since I have no NULLs. Given that, I think the NOT EXISTS could be a good solution, even on 8.3 (we're planning to upgrade, but it's not a feasible solution to this particular problem), no? Basically, it seems like the main issue with the current plans is the per-tuple seq scans on the full materializations. Adding correlation (by rewriting NOT IN as NOT EXISTS) prevents materialization, hence getting rid of the biggest performance problem. Thanks, --- Maciek Sakrejda | System Architect | Truviso 1065 E. Hillsdale Blvd., Suite 215 Foster City, CA 94404 (650) 242-3500 Main www.truviso.com
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