If you use the guarantee and it bumps the available maximum storage it can hang future updates until it can release some. Without the guarantee parameter setting it will release some anyway and continue processing. Other than that I'm not aware of any "its too big" or "its too old" performance issues. I suppose NOT getting a snapshot too old error on a very long running query sooner might be considered a performance benefit of having less retention, but I don't think that is what you're after. Regards, mwf _____ From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Braekeveld, Mathieu Sent: Friday, March 19, 2010 12:13 PM To: oracle-l@xxxxxxxxxxxxx Subject: undo retention parameter Hi, Question: Can a too high value in the undo retention parameter cause performance problems? And if so, why is that? Thanks for your help! This e-mail is personal. For our full disclaimer, please visit www.centric.eu/disclaimer.