Stephan Hmmm... not unless I'm missing it too ? :) something definetely smells fishy Let's take a look at those rows -- You can get the block number and the file number using dbms_rowid.rowid_block_number and dbms_rowid.rowid_relative_fno, respectively. Then use alter system dump datafile <fno> block <blockno>; to dump the block to a tracefile. It seems you indeed already have a row in there with that value. Also, what does select /*+ FULL (g) */ gds_host , rowid from gds_hosts g where rowid in (select row_id from exceptions); show ? ========================= Stefan P Knecht CEO & Founder s@xxxxxxxx 10046 Consulting GmbH Schwarzackerstrasse 29 CH-8304 Wallisellen Switzerland Phone +41-(0)8400-10046 Cell +41 (0) 79 571 36 27 info@xxxxxxxx http://www.10046.ch =========================