DB2 LUW 10.5-如何强制DB2存储过程将最新统计信息用于最优化的计划

Question

We see an issue occasionally. Stored procedure running a SQL runs very slow. Same SQL when run from command line runs very fast. It seems stored procedure uses a different path. The workaround for us is to drop and recreate the procedure, after which it picks up the right plan.

Is there a way to execute a stored procedure with an instruction to regenerate execution plan at run time, so as to get the best plan every time.

Answer 1

You probably don't want to recompile plans every time you call your procedure, as you lose the performance benefit of having the procedure in the first place.

When you do need to recompile it, which shouldn't happen too frequently in a stable environment, you can use the REBIND_ROUTINE_PACKAGE system stored procedure:

call SYSPROC.REBIND_ROUTINE_PACKAGE('P', 'YOUR_SP', '')

If you do decide that you want the plan to be recreated each time the procedure is called, you can set the REOPT ALWAYS bind option when you create the procedure, using the many ways described in the manual , for example by executing call SYSPROC.SET_ROUTINE_OPTS('REOPT ALWAYS) before creating the procedure