cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jonathan Colby <jonathan.co...@gmail.com>
Subject Re: Decorator Algorithm
Date Fri, 24 Jun 2011 12:31:13 GMT
thanks guys. That clears things up.

On Jun 24, 2011, at 4:53 AM, Maki Watanabe wrote:

> 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 <aaron@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


Mime
View raw message