Simple Oracle Query...but slow

Hello

I am using a query which takes arround .5 sec to execute.

select usr_id from table1,table2
where yy = '022021900'
and table1.usr_id = table2.usr_id
and table1.zz in ('000001005')

this query takes arround .5 sec ...but...if I write

select usr_id from table1,table2
where yy = '022021900'
and table1.usr_id = table2.usr_id
and table1.zz in ('000001005','000001005') <-- add new (same) value

this query only takes some milliseconds...

I analyzed explain plan and found out that the first query has a much greater "consistent get" than the 2nd query.

1 query) Consistent get: 85575
2nd query) Consistent get: 9

This problem occured recently on one of our oracle instances. If I use the same query in another oracle installation (not the same machine) then everything is OK. I also restarted the DB, but with no luck.

Thanks for helping

Michael Received on Mon Jan 26 2004 - 22:50:05 CST