> Hi, > > I have a perfomance issue : > > I run PG (8.0.3) and SQLServer2000 on a Windows2000 Server > (P4 1,5Ghz 512Mo) I have a table (3200000 rows) and I run > this single query : > > select cod from mytable group by cod > I have an index on cod (char(4) - 88 different values) > > PG = ~ 20 sec. > SQLServer = < 8 sec > > > the explain is : > > HashAggregate (cost=64410.09..64410.09 rows=55 width=8) > -> Seq Scan on mytable (cost=0.00..56325.27 rows=3233927 width=8) > > > if I switch to "enable_hashagg = false" (just for a try...) > the planner will choose my index : > > Group (cost=0.00..76514.01 rows=55 width=8) > -> Index Scan using myindex on mytable > (cost=0.00..68429.20 rows=3233927 > width=8) > > but performance will be comparable to previous test. > > So with or without using Index I have the same result.
Out of curiosity, what plan do you get from SQLServer? I bet it's a clustered index scan... //Magnus ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
