Hi Rich Also note that constraints can be validated in parallel. Cheers, Chris Antognini Troubleshooting Oracle Performance, Apress 2008 http://top.antognini.ch ------------------------------ Date: Thu, 15 Dec 2011 11:15:47 -0800 Subject: Re: How much time required to add constraint(s) From: Rich <richa03@xxxxxxxxx> Thanks all - outstanding. Now, I can roughly estimate time as well as avoid the lock. Thanks again, Rich -- //www.freelists.org/webpage/oracle-l