When you first install Adaptive Server, there are two abstract plan groups:
ap_stdout, used by default for capturing plans
ap_stdin, used by default for plan association
A System Administrator can enable server-wide plan capture to ap_stdout, so that all query plans for all queries are captured. Server-wide plan association uses queries and plans from ap_stdin. If some queries require specially-tuned plans, they can be made available server-wide.
A System Administrator or Database Owner can create additional plan groups, copy plans from one group to another, and compare plans in two different groups.
The capture of abstract plans and the association of abstract plans with queries always happens within the context of the currently-active plan group. Users can use session-level set commands to enable plan capture and association.
Some of the ways abstract plan groups can be used are:
A query tuner can create abstract plans in a group created for testing purposes without affecting plans for other users on the system
Using plan groups, “before” and “after” sets of plans can be used to determine the effects of system or upgrade changes on query optimization.
See Chapter 16, “Creating and Using Abstract Plans,” for information on enabling the capture and association of plans.
