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Posted to commits@cassandra.apache.org by Apache Wiki <wi...@apache.org> on 2010/03/27 02:14:47 UTC

[Cassandra Wiki] Update of "AntiEntropy" by JonathanEllis

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The "AntiEntropy" page has been changed by JonathanEllis.
http://wiki.apache.org/cassandra/AntiEntropy?action=diff&rev1=4&rev2=5

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+ !AntiEntropy means comparing all the replicas of each piece of data that exist (or are supposed to) and updating each replica to the newest version.
+ 
  Cassandra's implementation is modeled on Dynamo's, with [[ArchitectureAntiEntropy|modifications to support the richer data model]].  Quoting from [[http://www.allthingsdistributed.com/2007/10/amazons_dynamo.html|Amazon's Dynamo]] section 4.7,
  
    . To detect the inconsistencies between replicas faster and to minimize the amount of transferred data, Dynamo uses Merkle trees. A Merkle tree is a hash tree where leaves are hashes of the values of  individual keys. Parent nodes higher in the tree are hashes of their respective  children. The principal advantage of Merkle tree is that each branch of the tree  can be checked independently without requiring nodes to download the entire [...] data set.