Hi, Thanks everyone for the informative discussion on this topic. I think that for project I am involved in I must remove the risk, however small, of a row key collision, and append the original id (in my case a long) to the hash, whatever hash I use. I don't want to be in the situation where occasionally something goes wrong and needing to eliminate the possibility of a collision.
I was confused by a discussion in a book I was reading on HBase, "HBase in Action", which used MD5 directly as the row key, leaving the impression that this was a completely reliable way of creating unique row keys from strings. Jon
