@Override
  public void assignRowColumn(VectorizedRowBatch batch, int batchIndex, int columnNum,
      AggregationBuffer agg) throws HiveException {

    BytesColumnVector outputColVector = (BytesColumnVector) batch.cols[columnNum];
    Aggregation myagg = (Aggregation) agg;
    outputColVector.isNull[batchIndex] = false;

    try {
      Aggregation bfAgg = (Aggregation) agg;
      byteStream.reset();
      BloomKFilter.serialize(byteStream, bfAgg.bf);
      byte[] bytes = byteStream.toByteArray();

      outputColVector.setVal(batchIndex, bytes);
    } catch (IOException err) {
      throw new HiveException("Error encountered while serializing bloomfilter", err);
    } finally {
      IOUtils.closeStream(byteStream);
    }
  }
class for storing the current aggregate value.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/aggregates/VectorUDAFBloomFilter.java