Обсуждение: Ascending / Descending Indexes

In some SQL engines the engine doesn't need to define both Ascending and Descending indexes on the same column.  Does Postgres need to have indexes defined for both Ascending and Descending sorts?  We use quite a few of these types of sorts.

Best Regards

Michael Gould wrote:
> In some SQL engines the engine doesn't need to define both Ascending and
> Descending indexes on the same column.  Does Postgres need to have indexes
> defined for both Ascending and Descending sorts?  We use quite a few of
> these types of sorts.

A single btree index can be used for both cases.  (Unless you want some
columns ascending and other columns descending, in which case you need
to work extra.)

--
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support