On Tue, Aug 23, 2005 at 13:41:32 +1000, "Lenard, Rohan (Rohan)" <[EMAIL PROTECTED]> wrote: > I've read that indexes aren't used for COUNT(*) and I've noticed (7.3.x) > with EXPLAIN that indexes never seem to be used on empty tables - is > there any reason to have indexes on empty tables, or will postgresql > never use them.
count will use indexes if appropiate. The counts themselves are NOT in the indexes, so counts of significant fractions of a table (in particular of the whole table) won't benefit from indexes. You aren't going to get query speed ups by putting indexes on empty tables. However, they may be required if you have unique or primary keys declared in the table. You may want them to enforce some kinds of constraints. ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
