Yes, Cassandra partitioner is based on hash ring. Doubling number of nodes is the best cluster exctending policy I've ever seen, because it's zero-overhead.
Hashring - you get MD5 max (2^128-1), divide it by number of nodes (partitions) getting N points and then evenly distribute them across you ring. You can open Python script you used to generate the following output ans see how it works. I am on Cassandra 1.2.19 and I am following the documentation for adding existing nodes to a cluster<http://www.datastax.com/docs/1.1/cluster_management#adding-capacity-to-an-existing-cluster>. We are choosing to double our cluster from six to twelve. I ran the token generator. Based on what I read in the documentation, I expected to see the same first six tokens and six new tokens. Instead I see almost the same tokens but off by a few numbers. Is this expected? Should I change the similar tokens to the new ones? Am I doing it wrong? Here is the output I am dealing with. With six: DC #1: Node #1: 0 Node #2: 28356863910078205288614550619314017621 Node #3: 56713727820156410577229101238628035242 Node #4: 85070591730234615865843651857942052863 Node #5: 113427455640312821154458202477256070484 Node #6: 141784319550391026443072753096570088105 With twelve: DC #1: Node #01: 0 Node #02: 14178431955039102644307275309657008810 Node #03: 28356863910078205288614550619314017620 Node #04: 42535295865117307932921825928971026430 Node #05: 56713727820156410577229101238628035240 Node #06: 70892159775195513221536376548285044050 Node #07: 85070591730234615865843651857942052860 Node #08: 99249023685273718510150927167599061670 Node #09: 113427455640312821154458202477256070480 Node #10: 127605887595351923798765477786913079290 Node #11: 141784319550391026443072753096570088100 Node #12: 155962751505430129087380028406227096910
