Re: Index scan ???
От | Alvaro Herrera |
---|---|
Тема | Re: Index scan ??? |
Дата | |
Msg-id | Pine.LNX.4.44.0208040120530.29827-100000@cm-lcon1-46-187.cm.vtr.net обсуждение исходный текст |
Ответ на | Index scan ??? (Tourtounis Sotiris <tourtoun@csd.uoc.gr>) |
Список | pgsql-general |
Tourtounis Sotiris dijo: > The first attribute is classified in descending order and there are > indexes on it and to the third atribute respectively. I make some SQL > questions on them in order to use the created b-trees on the first > attribute and for 3-4 times there isan index scan on it as it used to > be. However, after those 3-4 times the database start to use > sequential scan on this first index. I don't really believe the query plan simply changes without something else changing (query or data). Note that different queries _will_ have different plans: ones will use index, others will not. Also, concurrent updates may be altering what you are seeing. See the FAQ about indexes not being used. -- Alvaro Herrera (<alvherre[a]atentus.com>) "Find a bug in a program, and fix it, and the program will work today. Show the program how to find and fix a bug, and the program will work forever" (Oliver Silfridge)
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