Performance : Optimize query

Hi Everybody,


I have this  following query : select count(*) from "Data" where
"IDOrigin"='29';
It's take more less 2 minutes to run... It's really slow...
Some one maybe knows about how to optimize "select count"

Below, there are the expalin analyse of the query.


EXPLAIN ANALYZE select count(*) from "Data" where "IDOrigin"='29';
NOTICE:  QUERY PLAN:

Aggregate  (cost=108945.77..108945.77 rows=1 width=0) (actual
time=108845.29..108845.30 rows=1 loops=1)
  ->  Seq Scan on Data (cost=0.00..107152.11 rows=717462 width=0) (actual
time=18233.46..106927.60 rows=1457826 loops=1)
Total runtime: 108845.50 msec.


I did already a lot of optimization such as modify shared_buffers and
sort_mem...
But always too slow...


Thanks, Areski