Have you ever felt that the optimizer was persecuting you by picking plans at random ? Perhaps you’re not paranoid, perhaps it’s part of Oracle Corp’s. master plan to take over the world. If you look closely at the list of hidden parameters you’ll find that some details of this cunning plan have leaked. In 10.1.0.2 Oracle created a new parameter _optimizer_random_plan with the description “optimizer seed value for random plans”. Who knows what terrible effects we may see when the default value of this parameter changes.