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From jacques-n <...@git.apache.org>
Subject [GitHub] drill pull request: DRILL-3623: Use shorter query path for LIMIT 0...
Date Thu, 29 Oct 2015 01:28:14 GMT
Github user jacques-n commented on the pull request:

    https://github.com/apache/drill/pull/193#issuecomment-152047328
  
    Interesting. Can you explain where the time is coming from? It isn't clear to me why this
will have a big impact over what we had before. While you're pushing the limit down to just
above the scan nodes, we already had an optimization which avoided parallelization. Since
we're pipelined this really shouldn't matter much. Is limit zero not working right in the
limit operator? It should terminate upon receiving schema, not wait until a batch of actual
records (I'm wondering if it is doing the latter). Is sending zero records through causing
operators to skip compilation? In what cases was this change taking something from hundreds
of seconds to a few seconds? I'm asking these questions so I can better understand as I want
to make sure there isn't a bug somewhere else. Thanks!


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