Lessons of the trade : Data purge in databases..

Quick note to myself.. If you have a high volume transactional database and are looking to purge data from a table(s).. make sure you purge the data in small chunks. If you purge the data in larger chunks (rows), other processes trying to access the data on those tables have to go to the redo logs to access the data, since the purge job will put a lock on the table. This obviously adds latency to the queries.. So purge the data in smaller chunks (rows), forcing the database to flush the redo logs.