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From sureshsubbiah <...@git.apache.org>
Subject [GitHub] incubator-trafodion pull request #651: Trafodion 2140
Date Wed, 10 Aug 2016 18:05:49 GMT
Github user sureshsubbiah commented on a diff in the pull request:

    https://github.com/apache/incubator-trafodion/pull/651#discussion_r74297961
  
    --- Diff: core/sql/optimizer/RelSample.cpp ---
    @@ -925,7 +925,6 @@ RelExpr *RelSample::bindNode(BindWA *bindWA)
       RelExpr* myChild = child(0);
       if (myChild->getOperatorType() == REL_SCAN &&
           (static_cast<Scan*>(myChild))->isHbaseTable() &&
    -      myChild->selectionPred().entries() == 0 &&
    --- End diff --
    
    Thanks. That is an interesting observation. I had not thought of sampling and predicate
evaluation as being commutative. I suppose even if sampling ratio is small and/or predicate
selectivity is high, doing these two operations in either order will be statistically indistinguishable.
Thanks for explaining.


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