PL/SQL performs a portion of the transformation process. The largest portion of this is referred to as direct SQL. SQL update statements run directly against tables to perform simple transformation that does not require business logic. These processes are generally run in parallel on the database server (and are very CPU intensive). With the large chunk of data processed, the disk input/output (IO) performance is limiting. A high-performing storage area network (SAN) file system improves the overall system response time.