Re: Forcing query to use an index
От | Michael Nachbaur |
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Тема | Re: Forcing query to use an index |
Дата | |
Msg-id | 0E014EA3-4DC8-11D7-90E0-000A27935D5A@nachbaur.com обсуждение исходный текст |
Ответ на | Re: Forcing query to use an index (Stephan Szabo <sszabo@megazone23.bigpanda.com>) |
Список | pgsql-sql |
On Monday, Mar 3, 2003, at 14:09 US/Pacific, Stephan Szabo wrote: > If you're hitting all the rows in the table, there's only disadvantage > to using an indexscan (right now, given the way data is stored). If > you > were returning some fraction of the rows postgresql should hopefully > switch to a different plan (depending on the estimated costs). I should only ever get one match per record. This is the structure of the relevant tables: Customer --> Customer_Month_Summary ^ | EmailAddress There is one Customer_Month_Summary record per-customer-per-month, so I should only get one record out of the database. Additionally, since there are about 2000 customer records, but multiple months in the summary table, I'll never use the entire results of the summary table in one query.
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