Optimize querry sql

Hi,

I had errors in my last emails. sorry

I want to optimize my query sql (execution time : 2665 ms) :

SELECT b.idxreseller, sum(a.nbrq), b.namereseller from stat a
,reseller b where b.asp=6 and a.idxreseller=b.reseller and
a.month=date_part('month',now() - interval '1 month') and
a.year=date_part('year',now() - interval '1 month') GROUP BY
b.idxreseller,b.namereseller limit 15;

Explain analyse :

Limit (cost=1057.15..1057.16 rows=1 width=27) (actual
time=2655.083..2655.176 rows=15 loops=1)
-> HashAggregate (cost=1057.15..1057.16 rows=1 width=27) (actual
time=2655.074..2655.132 rows=15 loops=1)
-> Nested Loop (cost=0.00..1057.14 rows=1 width=27) (actual
time=0.646..2464.563 rows=18543 loops=1)
-> Seq Scan on stat a (cost=0.00..1042.98 rows=1
width=8) (actual time=0.273..1239.510 rows=24881 loops=1)
Filter: (((month)::double precision =
date_part('month'::text, (now() - '1 mon'::interval))) AND
((year)::double precision = date_part('year'::text, (now() - '1
mon'::interval))))
-> Index Scan using reseller_pkey on reseller b
(cost=0.00..14.15 rows=1 width=23) (actual time=0.034..0.038 rows=1
loops=24881)
Index Cond: ("outer".idxrreseller = b.idxreseller)
Filter: (asp = 6)
Total runtime: 2655.713 ms

dns=> \d stat;
Table «public.stat»

idxreseller | integer | not null
idxdo | integer | not null
idxd | integer | not null
nbrq | integer | default 0
month | integer | default date_part('month'::text, (now() -
'1 mon'::interval))
year | integer | default date_part('year'::text, (now() - '1
mon'::interval))

Index :
«stat_dns_domaine_idx_idxr_idxreseller» btree (dxreseller)
«stat_dns_domaine_idx_month_year_idxres» btree (month, year, idxreseller)

\d reseller;
Table «public.reseller»

idxreseller | integer | not null default
nextval(('idxrevendeur_seq'::text)::regclass)
namereseller | text |
asp | integer |
Index :
«reseller_pkey» PRIMARY KEY, btree (idxreseller)

Have you advices ?

Thank you

Stan