title: How to hash a GUID and a 64-bit timestamp into another GUID
body: <p>We're working with a proprietary database and have a table whose semantic compound key consists of a 128-bit GUID and a 64-bit timestamp. "Semantic compound key" in a sense that multiple records with the same GUID may occur in the table, as well as multiple records with the same timestamp; however the pair (GUID, timestamp) is unique. As an enhancement to better support the hashing mechanism, we could force the timestamp to be completely unique, e.g. by incrementing it by a millisecond.</p>
  
  <p>The proprietary database is rather minimalistic and has a 128-bit hash key which we would like to use for fast access. Thus we need to hash the GUID and the timestamp into a 128-bit field, i.e. into another GUID.</p>
  
  <p>Can you propose a hash function which may serve this purpose the best?</p>