Optimize SQL

Hi,

Is there anyway we can optimize this sql ? it is doing full table
scan on listing and address table . Postgres version 8.0.2

Thanks!
Pallav.

explain analyze
select listing0_.listingid as col_0_0_,
getmaxdate(listing0_.lastupdate, max(addressval2_.createdate)) as col_1_0_
from listing.listing listing0_
left outer join listing.address listingadd1_
on listing0_.fkbestaddressid=listingadd1_.addressid
left outer join listing.addressvaluation addressval2_
on listingadd1_.addressid=addressval2_.fkaddressid
where listing0_.lastupdate>'2006-09-15 08:31:26.927'
and listing0_.lastupdate<=current_timestamp
or addressval2_.createdate>'2006-09-15 08:31:26.927' and
addressval2_.createdate<=current_timestamp
group by listing0_.listingid , listing0_.lastupdate
order by getmaxdate(listing0_.lastupdate, max(addressval2_.createdate))
asc limit 10;

Limit (cost=2399501.49..2399501.51 rows=10 width=20) (actual time=414298.076..414298.174 rows=10 loops=1)
-> Sort (cost=2399501.49..2410707.32 rows=4482333 width=20) (actual time=414298.068..414298.098 rows=10 loops=1)
Sort Key: getmaxdate(listing0_.lastupdate, max(addressval2_.createdate))
-> GroupAggregate (cost=1784490.47..1851725.47 rows=4482333 width=20) (actual time=414212.926..414284.927 rows=2559 loops=1)
-> Sort (cost=1784490.47..1795696.31 rows=4482333 width=20) (actual time=414174.678..414183.536 rows=2563 loops=1)
Sort Key: listing0_.listingid, listing0_.lastupdate
-> Merge Right Join (cost=1113947.32..1236714.45 rows=4482333 width=20) (actual time=273257.256..414163.920 rows=2563 loops=1)
Merge Cond: ("outer".fkaddressid = "inner".addressid)
Filter: ((("inner".lastupdate > '2006-09-15 08:31:26.927'::timestamp without time zone) AND ("inner".lastupdate <= ('now'::text)::timestamp(6) with time zone)) OR (("outer".createdate > '2006-09-15 08:31:26.927'::timestamp without time zone) AND ("outer".createdate <= ('now'::text)::timestamp(6) with time zone)))
-> Index Scan using idx_addressvaluation_fkaddressid on addressvaluation addressval2_ (cost=0.00..79769.55 rows=947056 width=12) (actual time=0.120..108240.633 rows=960834 loops=1)
-> Sort (cost=1113947.32..1125153.15 rows=4482333 width=16) (actual time=256884.646..275823.217 rows=5669719 loops=1)
Sort Key: listingadd1_.addressid
-> Hash Left Join (cost=228115.38..570557.39 rows=4482333 width=16) (actual time=93874.356..205054.946 rows=4490963 loops=1)
Hash Cond: ("outer".fkbestaddressid = "inner".addressid)
-> Seq Scan on listing listing0_ (cost=0.00..112111.33 rows=4482333 width=16) (actual time=0.026..25398.685 rows=4490963 loops=1)
-> Hash (cost=183333.70..183333.70 rows=6990270 width=4) (actual time=93873.659..93873.659 rows=0 loops=1)
-> Seq Scan on address listingadd1_ (cost=0.00..183333.70 rows=6990270 width=4) (actual time=13.256..69441.056 rows=6990606 loops=1)