Crear los indices adecuados

Hola a Todos,

Tengo una tabla con muchos campos, ademas que tiene como 3 millones de
registros, de esas tabla hay 16 campos
que se usaran de manera combinada para realizar consulta, como son
muchos query con distintas combinaciones y condicionales, en base al
ejemplo que les envio, quisiera una buena sugerencia para crear los
inidice y que la consulta sea liviana, en estos momentos mis tiempos
son muy altos, El caso es:

Mi tabla es:

linea | character varying(2) |
anio | character varying(4) |
semestre | character varying(1) |
trimestre | character varying(1) |
mes | character varying(2) |
dia | character varying(2) |
fecha | character varying(8) |
anio_ser | character varying(4) |
semestre_ser | character varying(1) |
trimestre_ser | character varying(1) |
mes_ser | character varying(2) |
dpto_cod | character varying(3) |
dpto_desc | character varying(30) |
mun_cod | character varying(3) |
mun_desc | character varying(30) |
geren_cod | character varying(6) |
geren_desc | character varying(30) |
gerente | character varying(30) |
region_cod | character varying(7) |
region_desc | character varying(30) |
super_cod | character varying(8) |
super_desc | character varying(30) |
ruta | character varying(20) |
punto_cod | character varying(3) |
punto_desc | character varying(30) |
neg_cod | character varying(3) |
neg_desc | character varying(30) |
cliente_cod | integer |
cliente_desc | character varying(40) |
grupo_cod | character varying(3) |
grupo_desc | character varying(30) |
div_cod | character varying(3) |
div_desc | character varying(30) |
marca_cod | character varying(3) |
marca_desc | character varying(30) |
pres_cod | character varying(3) |
pres_desc | character varying(30) |
tam_cod | character varying(3) |
tam_desc | character varying(30) |
prod_cod | character varying(25) |
prod_desc | character varying(30) |
vta_cajas | numeric(31,7) |
vta_divisa | numeric(31,7) |

Necesito consultar por ejemplo
Query 1
=======
SELECT
V.geren_cod,V.geren_desc,V.ruta,V.ruta,V.cliente_cod,V.cliente_desc,V.anio,V.anio,SUM(V.vta_cajas)
as
cajas,SUM(V.vta_divisa) as divisa FROM dm.venta V WHERE V.anio
IN(2007,2006,2005) GROUP BY
V.geren_cod,V.geren_desc,V.ruta,V.cliente_cod,V.cliente_desc,V.anio ORDER
BY
V.geren_desc,V.geren_cod,V.ruta,V.cliente_desc,V.cliente_cod,V.anio DESC

Query2
======
SELECT
V.geren_cod,V.geren_desc,V.cliente_cod,V.cliente_desc,V.anio,V.anio,SUM(V.vta_cajas)
as cajas,SUM(V.vta_divisa) as divisa
FROM dm.venta V WHERE V.anio IN(2007,2006,2005) GROUP BY
V.geren_cod,V.geren_desc,V.cliente_cod,V.cliente_desc,V.anio ORDER BY
V.geren_desc,V.geren_cod,V.cliente_desc,V.cliente_cod,V.anio DESC

Tengo la mas grande donde van casi todos los campos.

explain analyze SELECT
V.geren_cod,V.geren_desc,V.geren_cod,V.gerente,V.region_cod,V.region_desc,V.super_cod,V.super_desc,V.ruta,V.ruta,V.cliente_cod,V.cliente_desc,V.punto_cod,V.punto_desc,V.neg_cod,V.neg_desc,V.grupo_cod,V.grupo_desc,V.div_cod,V.div_desc,V.marca_cod,V.marca_desc,V.pres_cod,V.pres_desc,V.tam_cod,V.tam_desc,V.prod_cod,V.prod_desc,V.dpto_cod,V.dpto_desc,V.mun_cod,V.mun_desc,V.anio,SUM(V.vta_cajas)
as cajas,SUM(V.vta_divisa) as divisa FROM dm.venta V WHERE V.anio=2007 or
V.anio=2006 or V.anio=2005 GROUP BY
V.geren_cod,V.geren_desc,V.gerente,V.region_cod,V.region_desc,V.super_cod,V.super_desc,V.ruta,V.cliente_cod,V.cliente_desc,V.punto_cod,V.punto_desc,V.neg_cod,V.neg_desc,V.grupo_cod,V.grupo_desc,V.div_cod,V.div_desc,V.marca_cod,V.marca_desc,V.pres_cod,V.pres_desc,V.tam_cod,V.tam_desc,V.prod_cod,V.prod_desc,V.dpto_cod,V.dpto_desc,V.mun_cod,V.mun_desc,V.anio
ORDER BY
V.geren_desc,V.geren_cod,V.gerente,V.region_desc,V.region_cod,V.super_desc,V.super_cod,V.ruta,V.cliente_desc,V.cliente_cod,V.punto_desc,V.punto_cod,V.neg_desc,V.neg_cod,V.grupo_desc,V.grupo_cod,V.div_desc,V.div_cod,V.marca_desc,V.marca_cod,V.pres_desc,V.pres_cod,V.tam_desc,V.tam_cod,V.prod_desc,V.prod_cod,V.dpto_desc,V.dpto_cod,V.mun_desc,V.mun_cod,V.anio
DESC;

QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort (cost=238008.81..238297.98 rows=115667 width=437) (actual
time=143460.996..143754.395 rows=211412 loops=1)
Sort Key: geren_desc, geren_cod, gerente, region_desc, region_cod,
super_desc, super_cod, ruta, cliente_desc, cliente_cod, punto_desc,
punto_cod, neg_desc, neg_cod, grupo_desc, grupo_cod, div_desc, div_cod,
marca_desc, marca_cod, pres_desc, pres_cod, tam_desc, tam_cod, prod_desc,
prod_cod, dpto_desc, dpto_cod, mun_desc, mun_cod, anio
-> HashAggregate (cost=226546.43..228281.43 rows=115667 width=437)
(actual time=17964.950..18908.797 rows=211412 loops=1)
-> Index Scan using venta_idxanio on venta v
(cost=0.00..131121.40 rows=1156667 width=437) (actual time=0.139..3269.739
rows=1405855 loops=1)
Total runtime: 143944.487 ms

Agradeceria sugerencias.

Saludos,