Help, need to disable undo, but how?

Question

I need to delete LOTS of rows from a table, but every time i hit the maxmum undo tablespace...
i have no room on disks to enlarge undo tablespace.
There are just to many rows to do it in parts and commit every part, i just want to have one delete query.
Is there a way to disable the undo system temporarily, then delete all the rows, and then enable it again?
The database is not in use right now, so i can do anything if needed.
Please help, thanx!

Answer 1

Is there a way to disable the undo system
temporarily, then delete all the rows, and then
enable it again?No.
The UNDO is there to protect the database.
There are several techniques you could try - search this forum for 'eliminate undo' or 'reduce undo'. But the important thing is to either reduce the size of the transaction or to increase the size of the undo - even if only temporarily.
Several techniques to reduce the size of the transaction:
- introduce extra commits (and risk getting ora-01555);
- insert the rows to be saved into a new table, truncate the original, possibly return saved rows to old table;
- stage the changes by repeatedly updating, each time setting a few of the columns to NULL followed by commits (assumption is that before image of only changed columns gets into undo) and finally deleting the rows, now that the only thing left is the key.
Message was edited by:
Hans Forbrich
PS: I'm alwasys willing to learn why my ideas won't work. Helps me learn what actually will work. <g>