https://svn.apache.org/repos/asf/cassandra/trunk/src/java/org/apache/cassandra/dht/OrderPreservingPartitioner.java
On Sun, Aug 22, 2010 at 10:46 AM, Hien. To Trong <hie...@vng.com.vn> wrote: > Hi, > I am developing a system with some features like cassandra. > I want to add order preserving partitioning strategy, but I don't know how to > implement it. > > In cassandra paper - Cassandra - A Decentralized Structured Storage System > "Cassandra partitions data across the cluster using consistent hashing but > uses an order pre- > serving hash function (OPHF) to do so" > > I wonder: > > 1. Cassandra still use a hash function (the other strategy is random > partitioner) for OPP? > If so, what is the algorithm of OPHF? is it a type of minimal perfect hash > function (MPHF)? > > I already read some papers about algorithms for MPHF which preserve the order > of hash value. However, > the size of key space equals and hash value space are equal and much more > smaller than the size of key space > (may be userid or usertaskid) in our application. How can I deal with that or > I went on the wrong track? > > 2. My system is simple. I have some servers and I use Berkeley DB to store > Key/Value (our data model is simple). Is OPP strategy useful > when I don't have data model like cassandra? (column family for example). > > Thanks so much.
