@Override
    public void aggregateInput(AggregationBuffer agg, VectorizedRowBatch batch)
    throws HiveException {

      int batchSize = batch.size;

      if (batchSize == 0) {
        return;
      }

      Aggregation myagg = (Aggregation)agg;
      myagg.count += batchSize;
    }
class for storing the current aggregate value.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/aggregates/VectorUDAFCountStar.java