CBQT-ORE and its FIRST_ROWS optimization inability
CBQT-ORE and its FIRST_ROWS optimization inability Terminology: CBQT: cost based query transformation ORE: or expansion Some days ago, I took a look on a customer’s performance issue which was introduced after their upgrade from 12.1 to 19c. Quite fast we could narrow it down to a new optimizer feature „cost based or expansion“. To get […]