Is your undo retention really set to 5.5 hours, or was 20000 a typo? On Tue, Mar 16, 2010 at 4:48 AM, dba1 mcc <mccdba1@xxxxxxxxx> wrote: > we have ORACLE 10.2.0.4 on UNIX system. Recently one of our databases has > ORA-0155 error happen several times. this database already setup: > > 1. undo_retention = 20000 > > 2. undo data file size current is 9 GB and can autoextend to 25 GB > > how come we still get ORA-01555 error? > > Thanks. > > > > > -- > //www.freelists.org/webpage/oracle-l > > >