Re: sequence scan problem
От | John Beaver |
---|---|
Тема | Re: sequence scan problem |
Дата | |
Msg-id | 48680D63.8090107@gmail.com обсуждение исходный текст |
Ответ на | Re: sequence scan problem (Jeremy Harris <jgh@wizmail.org>) |
Список | pgsql-performance |
Oh, and the version is 8.3.3. Jeremy Harris wrote: > John Beaver wrote: >> I'm having a strange problem with a query. The query is fairly >> simple, with a few constants and two joins. All relevant columns >> should be indexed, and I'm pretty sure there aren't any type >> conversion issues. But the query plan includes a fairly heavy seq >> scan. The only possible complication is that the tables involved are >> fairly large - hundreds of millions of rows each. >> >> Can anyone explain this? There should only ever be a maximum of about >> 50 rows returned when the query is executed. > > You didn't say when you last vacuumed? > If there should only be 50 rows returned then the estimates from the > planner are way out. > > If that doesn't help, we'll need version info, and (if you can afford > the time) an "explain analyze" > > Cheers, > Jeremy >
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