public static boolean strictMerge(ReduceSinkOperator cRS, ReduceSinkOperator pRS)
          throws SemanticException {
    return strictMerge(cRS, ImmutableList.of(pRS));
  }
This is a more strict version of the merge check, where:
- cRS and pRS should have exactly the same keys in the same positions, and
- cRS and pRS should have exactly the same partition columns in the same positions, and
- cRS and pRS should have exactly the same bucket columns in the same positions, and
- cRS and pRS should sort in the same direction
ql/src/java/org/apache/hadoop/hive/ql/optimizer/correlation/ReduceSinkDeDuplicationUtils.java