Re: BUG #6702: SELECT Query on INDEX
От | Kevin Grittner |
---|---|
Тема | Re: BUG #6702: SELECT Query on INDEX |
Дата | |
Msg-id | 4FE4452402000025000489C7@gw.wicourts.gov обсуждение исходный текст |
Ответ на | BUG #6702: SELECT Query on INDEX (alokrawat0212@gmail.com) |
Список | pgsql-bugs |
<alokrawat0212@gmail.com> wrote: > I created a Index in postgres.Now i want to fire select query in > this Index and check data. > > Please tell me how to perform this??? This is not a bug. Please post any follow-ups or similar questions to pgsql-general or pgsql-novice; or if it is a performance question, try pgsql-performance. To answer the question, as long as we're here, PostgreSQL uses a cost-based optimizer -- so it will consider using the index on any queries for the table which reference indexed columns. On a tiny table (a few thousand rows or less), or if you are selecting more than about 10% of the rows from the table, it is unlikely to use the index because a simple scan of the heap is almost always faster. Load up the tables with a lot of data and select for equality against an indexed column using a value present in a small number of rows, and you are likely to see the index used. If you think the optimizer is not choosing the fastest plan, please read this page: http://wiki.postgresql.org/wiki/SlowQueryQuestions -Kevin
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