How to avoid "Seq Scans"?

[Vincenzo Romano <vincenzo(dot)romano(at)gmail(dot)com>]

Hi all.

In PG 8.2.4 I have a 4+M rows table like this:

create table t (
  f1 bigint,
  f2 text,
  f3 text
);

create index i_t_1 on t( f1 );
create index i_t_2 on t( f2 );
create index i_t_2 on t( f3 );

I'd need to write a stored function that should do the
following:

for rec in select * from t order by f2,f2 loop
...
end loop;

This loop is increadibly slow. Infact the friendly explain tells me
that:

test=# explain select * from t order by f2,f3;
                                   QUERY PLAN
---------------------------------------------------------------------------------
 Sort  (cost=958786.20..970734.55 rows=4779338 width=28)
   Sort Key: f2,f3
   ->  Seq Scan on t  (cost=0.00..85501.38 rows=4779338 width=28)

I'd like to know a hint about a technicque to avoid the sequential 
scan!

Thanks.

-- 
Vincenzo Romano
--
Maybe Computer will never become as intelligent as Humans.
For sure they won't ever become so stupid. [VR-1988]