How to tell IUS to use Index ?

Hello, i have a problem that on a SQL-statement an index is not used. Below the table-schema is shown. By the "unique"-definition an index is implicitly defined on the three columns (isn't it ?). create table B ( x integer not null references A1, y integer not null references A1, z integer not null references A2, unique(x, y, z) ); Now i have a temp table which is created the same way as the table B (three integer-columns named f, g and h). I want to delete all entries from table B that are listed in the temp table. Here we go: delete from B where row(x ,y ,z) IN (select row(f, g, h) from temp_tab); The problem is, that this statements takes a very long time to be executed. The index is not used, i guess. A select on the same table B is much faster (less than 1 second), but this statements takes about 20 seconds. Is there a solution for this ? Thank you in advance, Gert. -- Gert Brinkmann Software Development email: gbrinkmann@dimedis.de dimedis GmbH tel: +49 221 92 12 60 - 0 Habsburgerring 2-12 fax: - 99 50674 Koeln http://www.dimedis.de