Use Random for now. The OPHF is the same as the old one, i.e., not actually OP. :)
I'm pretty convinced at this point that it's impossible to have an order-preserving hash that doesn't either (a) impose a relatively short key length past which no partitioning is done (i.e., all keys w/ the same prefix go to the same node) or is (b) very sensitive to key length such that the keys with a given length N will not be evenly distributed across all nodes. Or both. So I am working on migrating from pluggable hash functions key -> BigInteger, to pluggable partitioning algorithms key -> EndPoint. Without the requirement to transform to a numeric value first I think I can create an order-preserving distribution that performs well. (I need this for range queries.) So far I have just laid the foundation, here: https://issues.apache.org/jira/browse/CASSANDRA-3 I hope to finish the rest tomorrow. -Jonathan On Wed, Mar 11, 2009 at 5:28 PM, Jiansheng Huang <[email protected]> wrote: > > Which one is better to use? The default is Random. > > In Avinash's annoucement mail, we have > (1) Ability to switch between a random hash and a OPHF. We still have the > old (wrong) OPHF in there. I will update it to the corrected one tomorrow. > > Is correct OPHF in? Thanks. >
