private long writeValueAndLength(KvSource kv) throws SerDeException {
    long valueOffset = writeBuffers.getWritePoint();
    kv.writeValue(writeBuffers);
    long tailOffset = writeBuffers.getWritePoint();
    writeBuffers.writeVLong(tailOffset - valueOffset);
    // LOG.info("Writing value at " + valueOffset + " length " + (tailOffset - valueOffset));
    return tailOffset;
  }
Writes the value and value length for non-first record.
@param kv Key-value writer.
@return The offset of the new record.
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/BytesBytesMultiHashMap.java