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.
Thanks for help.
Stéphane COEZ
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
