@Override
    public Void call() throws Exception {
      int batchSize = 1024;
      VectorUDFDateString udf = new VectorUDFDateString(0, 1);
      VectorizedRowBatch batch = new VectorizedRowBatch(2, batchSize);
      BytesColumnVector in = new BytesColumnVector(batchSize);
      LongColumnVector out = new LongColumnVector(batchSize);
      batch.cols[0] = in;
      batch.cols[1] = out;
      for (int i = 0; i < batchSize; i++) {
        byte[] data = String.format("1999-%02d-%02d", 1 + (i % 12), 1 + (i % 15)).getBytes("UTF-8");
        in.setRef(i, data, 0, data.length);
        in.isNull[i] = false;
      }
      udf.evaluate(batch);
      // bug if it throws an exception
      return (Void) null;
    }
Input array is used to fill the entire size of the vector row batch
ql/src/test/org/apache/hadoop/hive/ql/exec/vector/expressions/TestVectorDateExpressions.java