> Based on the explanation in the ticket, I am expecting it to not skip >running jobs for the inner queries which has limit / always false where >conditions.
The ticket says that the optimization does not apply for limits within the inner clauses, but should apply always if the outer query has a limit. It should be removing the workload parts for Tez (replaces all inputs with a 0 row table btw, does not skip the job). This optimization does not extend very well into MR when there are joins. I suspect the MR conditional tasks for joins which don't play nice with the null-scan optimization. Tez only does noconditional.task.size map joins, it never does guesswork in the middle of a query. Cheers, Gopal
