public Writable createRow() throws IOException {
    bytes = new BytesWritable();
    bytes.setCapacity(maxRecordLength);
    return bytes;
  }
Read from a binary stream and treat each 1000 bytes (configurable via
hive.binary.record.max.length) as a record.  The last record before the
end of stream can have less than 1000 bytes.
ql/src/java/org/apache/hadoop/hive/ql/exec/BinaryRecordReader.java