Yes, and it's been rejected. The notion is obviously bogus; it amounts to assuming that every database is a star schema with only one core table.
Interesting; yes, I suppose that's true.
Once we get into GEQO territory, we are using the left-deep-only heuristic because that's the only kind of plan GEQO can construct. But at that point you've already given up any notion of exhaustive search.
I think most applications would prefer an exhaustive, deterministic search of a subset of the search space over a non-exhaustive, non-deterministic search of the same subset, given approximately the same performance. In other words, if confining the search to left-deep plans allows people to use the normal planner in situations where they would normally be forced to use GEQO to get acceptable performance, I think that would be a win.
Speaking of which, why does GEQO restrict its search to left-deep plans only?
-Neil
---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
