On 03/03/2011 13:29, [email protected] wrote:
I use pgsql 9.0.3 and I know that postgresql tries to use the fields in
indexes instead of the original table if it possible
But when I run
SELECT COUNT(id) FROM tab
or
SELECT COUNT(*) FROM tab
where there "id" is PRIMARY KEY and there are other indexes there I get
execution plan that doesnt use any indexes, but sequentab scanning the
original table.
Because when you do SELECT COUNT(*) without any WHERE.... clause, then
PostgreSQL has to scan through *all* the rows in the table in order to
count them.
Ray.
--
Raymond O'Donnell :: Galway :: Ireland
[email protected]
--
Sent via pgsql-general mailing list ([email protected])
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
