valgog wrote:
On Jul 25, 2:14 am, Lew <[EMAIL PROTECTED]> wrote:
How about two indexes, one on each column? Then the indexes will cooperate
when combined in a WHERE clause.
<http://www.postgresql.org/docs/8.2/interactive/indexes-bitmap-scans.html>
I don't believe the index makes a semantic difference with regard to ascending
or descending. An index is used to locate records in the selection phase of a
query or modification command.
--
Lew
Ordered indexes (b-tree in this case) are also used to get the needed
record order and it is absolutely not necessary to have a WHARE clause
in your select statement to use them when you are using ORDER BY.
But does that affect anything when you "ORDER BY foo ASC" vs. when you "ORDER
BY foo DESC"?
For use by ORDER BY, separate column indexes are an even better idea.
--
Lew
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