Re: speeding up big query lookup
От | Ragnar |
---|---|
Тема | Re: speeding up big query lookup |
Дата | |
Msg-id | 1156585967.26837.103.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | speeding up big query lookup ("Silvela, Jaime \(Exchange\)" <JSilvela@Bear.com>) |
Список | pgsql-general |
On fös, 2006-08-25 at 18:34 -0400, Silvela, Jaime (Exchange) wrote: > This is a question on speeding up some type of queries. > > I have a very big table that catalogs measurements of some objects over > time. Measurements can be of several (~10) types. It keeps the > observation date in a field, and indicates the type of measurement in > another field. > > I often need to get the latest measurement of type A for object X. > The table is indexed by object_id. one popular way is to create a composite index: CREATE INDEX object_val_id_type_date ON object_val(object_id, object_val_type_id, observation_date); then you could SELECT * FROM object_val WHERE object_id=? AND object_val_type_id=? ORDER BY observation_date DESC LIMIT 1; Hope this helps gnari
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