private static ExprNodeDesc buildColumnDesc(
      VectorizationContext ctx,
      String column,
      TypeInfo typeInfo) {

    return new ExprNodeColumnDesc(
        typeInfo, column, "table", false);
  }
Unit test for the vectorized GROUP BY operator.
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/TestVectorGroupByOperator.java