RE: [GENERAL] Optimal indicies

Hi!

On Fri, 16 Apr 1999, Jackson, DeJuan wrote:
> try:
> EXPLAIN SELECT pos_id, rating
>  FROM pos_rating pr
>  WHERE date_i = current_date AND city_id = 2  AND
>  EXISTS (SELECT DISTINCT pos_id FROM positions p WHERE subsec_id = 1 AND
> status = 'A' AND pr.pos_id=p.pos_id)
> ORDER BY rating;

   This probably will help, thanks.

> Index date_i and city_id only.

   Why? How do I find (for any given query) what indices I do need?
Postgres (being just a program) definetely have a set of rules where to use
and where not to use indicies. Any way for us to know/understand these
rules? Any general rules?

>     -DEJ

Oleg.
----
    Oleg Broytmann     http://members.xoom.com/phd2/     phd2@earthling.net
           Programmers don't die, they just GOSUB without RETURN.