Re: Seq Scan
От | Tyler Durden |
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Тема | Re: Seq Scan |
Дата | |
Msg-id | ab07320e0706011017u55ceacd8tb428b89128a53975@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: Seq Scan ("John D. Burger" <john@mitre.org>) |
Ответы |
Re: Seq Scan
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Список | pgsql-general |
Yes, either case happens the same. I'm come recently from MySQL and it works in a different way. I find strange that a simple SELECT COUNT(...) is so slow with only 700 000 records. Has been a nightmare optimizing this tables/queries. Sorry about this silly question, but I'm new to Posgresql. Thanks, Tyler On 6/1/07, John D. Burger <john@mitre.org> wrote: > You mention SELECT COUNT(ID), but your example shows SELECT ID. In > either case, the planner is choosing the correct plan. Indexes exist > to save the engine from visiting every row in the table, but both of > these queries require every row to be visited anyway. > > Perhaps you think that these queries can be satisfied without > visiting the actual table rows at all, using only the index. This is > incorrect - PG doesn't work that way. > > - John Burger > MITRE > > > ---------------------------(end of broadcast)--------------------------- > TIP 5: don't forget to increase your free space map settings >
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