Github user gatorsmile commented on the pull request:
https://github.com/apache/spark/pull/10278#issuecomment-165507592
Thank you for your detailed explanation! @liancheng
I have the same opinion as @marmbrus . We should include CNF conversion
into our optimizer. Some RDBMS systems might put it during the phase of query
rewriting. Below is my 2 cents about CNF.
Generally, CNF conversion is an important concept in query optimization,
especially when we support indexing in Spark. When (multi-attribute) indexes
exist over some subset of conjucts, we can employ these indexes to improve the
selectivity.
Thanks!
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