Re: [GENERAL] Question about indexes.
От | jim@reptiles.org (Jim Mercer) |
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Тема | Re: [GENERAL] Question about indexes. |
Дата | |
Msg-id | m10pmrb-00080YC@mailbox.reptiles.org обсуждение исходный текст |
Ответ на | Question about indexes. ("Spolar Alejandro" <alejo@mecon.ar>) |
Список | pgsql-general |
> This table has no indexes at all. Each query made (using EXPLAIN) reveals a > "Seq Scan". > So far, everything is OK. > Then I define 2 indexes, one affects a varchar field, for example 'lastname' > an the other a float type field, let´s call it 'id'. > When I perform a query such as SELECT * FROM table WHERE lastname = > 'Douglas', EXPLAIN reveals that index is being used ("Index Scan"). > But when the query is like: SELECT * FROM table WHERE id = 10, no index is > used, a "Seq Scan" is made. So it looks like if an index defined on a > numeric type field, doesn't work. (same thing happens with an index on > integer field). > Finally I made the index on 'id' field CLUSTERED. Repeating the query using > EXPLAIN I get a lower cost and "Index Scan". i found a similar problem with 6.5beta, only i was using index fields of int8, float8, datestamp and abstime. be nice to know what the issue is. jim (wandering off to look up "CLUSTERED") -- [ Jim Mercer Reptilian Research jim@reptiles.org +1 416 410-5633 ] [ The telephone, for those of you who have forgotten, was a commonly used ] [ communications technology in the days before electronic mail. ] [ They're still easy to find in most large cities. -- Nathaniel Borenstein ]
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