private static OpAttr genMapSideGBNoSkewNoAddMRJob(OpAttr inputOpAf, HiveAggregate aggRel,
      GBInfo gbInfo) throws SemanticException {
    OpAttr mapSideGB = null;
    OpAttr mapSideRS = null;
    OpAttr reduceSideGB = null;

    // 1. Insert MapSide GB
    mapSideGB = genMapSideGB(inputOpAf, gbInfo);

    // 2. Insert MapSide RS
    mapSideRS = genMapSideGBRS(mapSideGB, gbInfo);

    // 3. Insert ReduceSide GB
    reduceSideGB = genReduceSideGB1(mapSideRS, gbInfo, false, false, GroupByDesc.Mode.MERGEPARTIAL);

    return reduceSideGB;
  }
GB-RS-GB1

Construct GB-RS-GB Pipe line. User has enabled Map Side GB, specified no
skew and Grp Set is below the threshold.

@param inputOpAf
@param aggRel
@param gbInfo
@return
@throws SemanticException
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/translator/opconventer/HiveGBOpConvUtil.java