Correcting Hash Join Estimates
От | mark.lubratt@indeq.com |
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Тема | Correcting Hash Join Estimates |
Дата | |
Msg-id | 20050404050803.7175.qmail@webmail10.mesa1.secureserver.net обсуждение исходный текст |
Ответы |
Re: Correcting Hash Join Estimates
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Список | pgsql-performance |
Hello! I posted a similar question to this one about a month ago; but, for some reason, it never seemed to be broadcast eventhough it ended up in the archives. So, since I'm still struggling with this, I thought I'd repost... I'm trying to optimize a query and the EXPLAIN ANALYZE (see link below) shows that some hash join row estimates are wrong by a factor of 2-3, and upwards of 7-8. There is a corresponding mis-estimation of the amount of time taken for these steps. The database is vacuum analyzed nightly by a cron job. How would I go about tightening up these errors? I suspect that I need to SET STATISTIC on some columns, but how can I tell which columns? Any help would be appreciated. WinXP (dual Xeon 1.2GB RAM) PgSQL 8.0.1 Explain Analyze: <http://www.indeq.com/EA.txt> View Definition: <http://www.indeq.com/VGAUA.txt> The largest table contains about 10,000 rows. All tables have indexes on their foreign keys. Thanks! Mark
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