Strategy to improve Oracle DELETE performance

Question

We\'ve got an Oracle 11g installation that is starting to get big. This database is the backend to a parallel optimization system running on a cluster. Input to the process

Answer 1

Deleting data is a hell of a job, for the database. It has to create before images, update indexes, write redo logs and remove the data. This is a slow process. If you can have a window to perform this task, easiest and fastest is to build new tables, containing the wanted data. Drop the old tables and rename the new tables. This requires some setup work, that is obvious but is very well possible to make. One step less drastic is to drop the indexes before the delete takes place. My vote would go for CTAS (Create Table As Select from) and build the new tables. A nice partitioning schema would certainly be helpful, maybe in the next release Oracle can combine interval and reference partitioning. It would be very nice to have.

Disabling logging .... can not be done for deletes but CTAS can use nologging. Make a backup when ready and make sure to transfer the datafiles to the standby database, if you have one.