Re: A question about update and insert/delete

In brief an update generates undo and changes to undo results in redo as does the update. The more data I change the more undo and redo generated. Then there are the indexes.

Even if Oracle was designed to only update what changed for the full row update it has to check every column compared to one for the single column update. For a 20 column row that is 19 additional compare operations.

I believe that Oracle only makes this test for indexed columns so that if you update an indexed column to itself no change is in fact made to the index but a full row update is forcing Oracle to do extra work that a single column update may not include.

HTH -- Mark D Powell -- Received on Fri Feb 04 2005 - 11:12:46 CST