Hi, All, We have some pretty big OLTP database suffer from ST enqueue contention (size range from 1TB-3TB), because we use dictionary managed tablespace and without proper extent size when table/index/context index got created. Now some indexes have tens of thousands of extents and whenever we drop some unused objects(like not used index via index monitoring), we suffer from ST enqueue, even during normal business operation time. We plan to use dbms_space_admin to convert existing DMT tbs to LMT tbs, and I already did some test on test box and it seems very good and pretty fast. Before do any change in production, ,I would like to ask you guys, if anyone has used it on big database and have any good/bad experience with it. Thanks for sharing. Regards -- Regards Zhu Chao www.cnoug.org -- //www.freelists.org/webpage/oracle-l