Looking for Rules on the Use (size) of ROLLBACK during UPDATE, DELETE, INSERT

I can't manage to calculate how many rbs space I need when I know the actions on my tables during DDL changes.

Example :
a table of 162+49MB extents, is supposed to be used up to 162 at least and 49MB at most.
If I apply an UPDATE on each row of this table (without any test), I would anticipate that RSB should use the useful space for a copy of the table and so, at least 162MB because I do not bother to calculate the real use of the second extent.

Some DBA told me once that he use the rule RBS=2*(updated object size) 4* for delete and 2* for an insert.

I do not understand the 2's or 4's and I experienced less than the size of the size of the first extent.

So, I am confused.

Could anybody enlights this for me ?

Thank you

Annie Received on Wed Dec 30 1998 - 13:49:32 CST