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From sureshsubbiah <...@git.apache.org>
Subject [GitHub] incubator-trafodion pull request #1163: [TRAFODION-2622] Left join with othe...
Date Thu, 06 Jul 2017 00:13:22 GMT
Github user sureshsubbiah commented on a diff in the pull request:

    https://github.com/apache/incubator-trafodion/pull/1163#discussion_r125786831
  
    --- Diff: core/sql/generator/GenPreCode.cpp ---
    @@ -2459,6 +2459,24 @@ RelExpr * Join::preCodeGen(Generator * generator,
     
             }
     
    +      // if we have both equi join preds and a beforejoin pred
    +      // Set a flag that will cause beforeJoinPred to be evaluated prior
    +      // join equi pred during execution. This helps with join explosion
    +      // if there are frequent matching values and the beforeJoinPred is
    +      // highly selective. There is no downside to evaluating beforeJoinPred
    +      // early, if it contains vids from outer only
    +      if (!(getEquiJoinPredicates().isEmpty() || getJoinPred().isEmpty() || 
    +	    isAntiSemiJoin()))
    +      {
    +	ValueIdSet dummy1, dummy2, dummy3, uncoveredPreds ;
    --- End diff --
    
    Thank you @zellerh. Will do.


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