Re: Simple Join
От | Mark Kirkwood |
---|---|
Тема | Re: Simple Join |
Дата | |
Msg-id | 43A1C40D.8040006@paradise.net.nz обсуждение исходный текст |
Ответ на | Re: Simple Join (Mitch Skinner <lists@arctur.us>) |
Ответы |
Overriding the optimizer
Re: Simple Join |
Список | pgsql-performance |
Mitch Skinner wrote: > I saw that; what I'm suggesting is that that you try creating a 3-column > index on ordered_products using the paid, suspended_sub, and id columns. > In that order, I think, although you could also try the reverse. It may > or may not help, but it's worth a shot--the fact that all of those > columns are used together in the query suggests that you might do better > with a three-column index on those. > > With all three columns indexed individually, you're apparently not > getting the bitmap plan that Mark is hoping for. I imagine this has to > do with the lack of multi-column statistics in postgres, though you > could also try raising the statistics target on the columns of interest. > > Setting enable_seqscan to off, as others have suggested, is also a > worthwhile experiment, just to see what you get. > > Right on. Some of these "coerced" plans may perform much better. If so, we can look at tweaking your runtime config: e.g. effective_cache_size random_page_cost default_statistics_target to see if said plans can be chosen "naturally". cheers Mark
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