Estimating rollback segment size

Group,

Is there a way to estimate the size of rollback segment based on an update statement? I have to update a table that has over 46K rows and the update will be a join between this and another table which has 2260 rows. I will be updating the 2 columns of the larger table and both of these are a varchar2 column.

The current size of the rollback segment is 1500 MB and when I try to run the update, it runs out of rollback segment space with the error below

ERROR at line 1:
ORA-01562: failed to extend rollback segment number 7 ORA-01650: unable to extend rollback segment RB7 by 515 in tablespace RBS Thanks Received on Thu Aug 24 2006 - 09:10:06 CDT