Why REBIND in DB2 9 for z/OS?
The obvious answer is to take advantage of optimizer improvements in DB2 9 for z/OS. However, that is not the only reason to rebind. Each release may introduce a revised format for the SQL runtime structures. While packages from a prior release will execute in the new release, there are performance overheads that occur because DB2 has to perform a translation of runtime structures. In some cases, the runtime optimizations that were created at the last rebind may be invalidated. A good example is an SPROC (Select PROCedure), which is also known as fast column processing. Basically, DB2 will set up a structure that supports faster movement of the rows internally. The general rule of thumb is that the CPU saving is in the range of 0-10%, dependent on the complexity of the statement and number of columns retrieved. And while a migration to DB2 9 will invalidate this runtime saving and thus introduce a CPU overhead of 0-10%, a REBIND will re-establish these SPROCs Another reason to REBIND i
