Re: CREATE INDEX .. ON table1 (field1 asc, field2 desc)
От | Bruce Momjian |
---|---|
Тема | Re: CREATE INDEX .. ON table1 (field1 asc, field2 desc) |
Дата | |
Msg-id | 200209020250.g822oU121626@candle.pha.pa.us обсуждение исходный текст |
Ответ на | Re: CREATE INDEX .. ON table1 (field1 asc, field2 desc) (Bruno Wolff III <bruno@wolff.to>) |
Список | pgsql-general |
Is this a TODO item? --------------------------------------------------------------------------- Bruno Wolff III wrote: > On Sun, Aug 25, 2002 at 10:00:56 +1000, > Martijn van Oosterhout <kleptog@svana.org> wrote: > > On Sat, Aug 24, 2002 at 08:18:25PM +0500, Timur wrote: > > > Hello! > > > > > > I am new to PostgreSQL and databases in general, and I have this > > > question: why it is not possible to specify ordering when creating an > > > index? > > > > > > Let's say I have a query which looks like this: > > > SELECT * FROM table1 > > > ORDER BY field1, field2 DESC > > > LIMIT 100; > > > > > > Apparently, system won't use index ON (field1, field2) .. > > > > It will if you do: > > SELECT * FROM table1 > > ORDER BY field1 DESC, field2 DESC > > LIMIT 100; > > > > Time to go read that SQL book again? > > That may or may not be his problem. If the order he wants is > order by field1 ASC, fiels2 DESC there isn't a simple way to create > a matching index. > > ---------------------------(end of broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/users-lounge/docs/faq.html > -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073
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