Github user jinfengni commented on the pull request:
https://github.com/apache/drill/pull/193#issuecomment-152034091
Sudheesh and I feel this new approach is more like a big optimization step
towards solving the performance issue for "limit 0" query, rather than hack
solution : 1) It shows quite significantly reduction in query time, from
hundreds of seconds to couple of seconds in some cases. That's a big
improvement. 2) it would benefit not only schema-based query, but also
schema-less query, while the original approach would only apply for
schema-based query.
I agree we should continue to optimize "limit 0" query. But for now, I
think this new approach has its own merits.
The aggregation /implicit casting are the two things that I can think of,
if we go with the schema-based approach.
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