[MonetDB-users] Best way to lookup a varchar field?

Hi, I've got a very simple table structure in SQL, with a non-unique varchar field and a few other fields including a CLOB. I found that it's abnormally slow to filter the varchar field with an 'IN' statement and simply return the CLOB. i.e.: select clob from x where varchar in ('a','b','c') With a couple million rows, the query is in multiple seconds if the results are around a couple thousand rows. Is there something I'm doing wrong? I should be just the varchar BAT filter, then join on the CLOB BAT. Should I manually assign the varchars to integers in another table and use ints on this table? That would be surprising... Thanks. H