On Mon, Aug 24, 2015 at 4:50 PM, Sungwook Yoon <[email protected]> wrote:
> Still, the performance drop down due to OR filtering is just astounding... > That is what query optimizers are for and why getting them to work well is important. The difference in performance that you are observing is not surprising given the redundant work that you are seeing. Using the OR operator prevents any significant short-circuiting and the repeated conversion operations that are happening make the evaluation much more expensive than it would otherwise be (a dozen extra copies where only one is needed). Other queries that can be subject to similar problems include common table expressions that read the same (large) input file many times. So far, Drill doesn't optimize all such expressions well.
