Re: A *short* planner question
От | Nick Fankhauser |
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Тема | Re: A *short* planner question |
Дата | |
Msg-id | NEBBLAAHGLEEPCGOBHDGMEDFEMAA.nickf@ontko.com обсуждение исходный текст |
Ответ на | Re: A *short* planner question (Tom Lane <tgl@sss.pgh.pa.us>) |
Ответы |
Re: A *short* planner question
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Список | pgsql-admin |
> Hmm. If the outer side of the nestloop were actually hitting 2696 rows > on average, it wouldn't be "lightning fast". So the planner's failure > to choose this plan is probably due to this overestimate. This may be a reasonable estimate- as you might have gathered, we're matching people to court cases. The typical person (hopefully) only has one case that they're involved with, but an attorney may be in the 1K-10K range and a judge in 10k-100K. Since they all live in the same table, the estimate may not be all that far off. In addition, since we're using a "like", typing in only an initial char would get roughly 1/26 of the rows back- Does the planner look at the number of leading chars provided when coming up with a plan? > still on 7.1.*, right? It'd be interesting to know if 7.2 gets > this right; it has more detailed stats and hopefully would make a better > estimate of the number of matches. 7.2 on our development box is on the middle-priority TODO list. (2-4 weeks.) I'll provide feedback when we get there. As always, thanks for the help! -Nick -------------------------------------------------------------------------- Nick Fankhauser nickf@ontko.com Phone 1.765.935.4283 Fax 1.765.962.9788 Ray Ontko & Co. Software Consulting Services http://www.ontko.com/
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