if this is a major effort, ask them to show a proof of concept that this will improve performance. Ask for tangibles results. For example, the response time for this screen during the day at peak usage is 'X', doing this will reduce response time by 'Y'. Or it will reduce CPU usage(and you really need to reduce CPU usage because you need to add more usage) and have him prove it to you. Logic doesn't matter. Make them prove it. You can always test performance. Have them transport a production tablespace to another instance and run tests. If you do not see any tangible results(not just reduced numbers from readings in the database, but actual improvement in performance) its not worth the effort. Typically putting up this kind of roadblock kills silly ideas, since the people who come up with them don't want to work that hard to prove to you that they will do anything.