Re:"System...forcing query plan" comments. (Score 1)

From the abstract: "A suggested query execution plan is used as a constraint on a guided optimization process such that all execution plans that do not conform to the suggested execution plan are eliminated as possible alternatives." Clearly, they are not talking about enforcing a specific (single) execution plan, but rather, using a plan (or more likely a part of plan) to control which plans will be considered. Sounds like execution plan tree pruning, aka hinting. You should read (at least the abstract) before you write.