@Override
  public boolean matches(String name, ColumnVector.Type inputColVectorType,
      ColumnVector.Type outputColVectorType, Mode mode) {

    /*
     * Count null input which is for COUNT(*) and output is LONG.
     *
     * Just modes (PARTIAL1, COMPLETE).
     */
    return
        name.equals("count") &&
        inputColVectorType == null &&
        outputColVectorType == ColumnVector.Type.LONG &&
        (mode == Mode.PARTIAL1 || mode == Mode.COMPLETE);
  }
class for storing the current aggregate value.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/aggregates/VectorUDAFCountStar.java