When you use showplan, Adaptive Server displays the optimized plan for a given query before it runs the query. When the query plan involves parallel processing, and a runtime adjustment is made, showplan displays this message, followed by the adjusted query plan:
AN ADJUSTED QUERY PLAN IS BEING USED FOR STATEMENT 1 BECAUSE NOT ENOUGH WORKER PROCESSES ARE CURRENTLY AVAILABLE. ADJUSTED QUERY PLAN:
When using set notexec, Adaptive Server does not attempt to execute a query, so runtime plans are never displayed.