public WriteBuffers getWriteBuffers() {
    return writeBuffers;
  }
A store for a bytes key for a hash set in memory.

The memory is a "infinite" byte array as a WriteBuffers object.

We give the client (e.g. hash set logic) a 64-bit key and count reference to keep that
has the offset within the "infinite" byte array of the key.  The 64 bits includes about half
of the upper hash code to help during matching.

We optimize the common case when the key length is short and store that information in the
64 bit reference.

Cases:

 1) One element when key and is small (and stored in the reference word):

   Key and Value Reference
     |
     | absoluteOffset
     |
     |
     v
     &lt;Key Bytes&gt;
       KEY

 2) One element, general: shows optional big key length.

  Key and Value Reference
     |
     | absoluteOffset
     |
     |
     v
     [Big Key Length] &lt;Key Bytes&gt;
       optional           KEY
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/mapjoin/fast/VectorMapJoinFastBytesHashSetStore.java