a quick followup on this : when using Byte ordered partitioner. how does a short key get mapped to the 128bit token ? what about keys longer than 128 ? does Cassandra just pad and truncate ?
thanks Le 24 juin 2011 04:53, "Maki Watanabe" <watanabe.m...@gmail.com> a écrit : > A little addendum > > Key := Your data to identify a row > Token := Index on the ring calculated from Key. The calculation is > defined in replication strategy. > > You can lookup responsible nodes (endpoints) for a specific key with > JMX getNaturalEndpoints interface. > > maki > > > 2011/6/24 aaron morton <aa...@thelastpickle.com>: >> Various places in the code call IPartitioner.decorateKey() which returns a DecoratedKey<T> which contains both the original key and the Token<T> >> >> The RandomPartitioner md5 to hash the key ByteBuffer and create a BigInteger. OPP converts the key into utf8 encoded String. >> >> Using the token to find which endpoints contain replicas is done by the AbstractReplicationStrategy.calculateNaturalEndpoints() implementations. >> >> Does that help? >> >> ----------------- >> Aaron Morton >> Freelance Cassandra Developer >> @aaronmorton >> http://www.thelastpickle.com >> >> On 23 Jun 2011, at 19:58, Jonathan Colby wrote: >> >>> Hi - >>> >>> I'd like to understand more how the token is hashed with the key to determine on which node the data is stored - called decorating in cassandra speak. >>> >>> Can anyone share any documentation on this or describe this more in detail? Yes, I could look at the code, but I was hoping to be able to read more about how it works first. >>> >>> thanks. >> >> > > > > -- > w3m
