Slow query, can't see why

I have a query hat does :

DELETE FROM TABLE_A WHERE ID NOT IN (SELECT ID FROM TABLE_B) and it's taking ages to run (it's not finished yet after 20 minutes)

TABLE_A has 64,000 rows
TABLE_B has 13 rows

So I would assume Oracle would compare each of the 64,000 rows in TABLE_A, to 13 values it stored in memory, and that should happen in a flash. I mean, 64k rows is nothing.

The plan does a full table scan on both tables, which is normal, and the query is 95% CPU and this machine is normally pretty fast.

Can anyone comment ? I may be missing something obvious.

Thanks
Syltrem Received on Fri Jun 22 2012 - 16:06:14 CDT