On Tue, 7 Oct 2003, Paul Serby wrote:
> Why does '*select count(id) from "tblContacts"'* do a sequential scan
> when the field '*id*' is indexed using a btree?
>
> MySql simply looks at the index which is keeping a handy record of the
> number of rows.
>
> Can anybody explain how and why postgres does this query like it does?
It's a FAQ I believe.
MySQL can tell you from it's index because it doesn't care if it gives you the
right number or not.
--
Nigel Andrews