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From "Timo Kinnunen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4775) Counters 2.0
Date Sat, 22 Jun 2013 17:13:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4775?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13691193#comment-13691193
] 

Timo Kinnunen commented on CASSANDRA-4775:
------------------------------------------

I read a paper called A comprehensive study of Convergent and Commutative Replicated Data
Types, which specifies an eventually consistent increment/decrement counter, among other things.
It's available here: http://hal.inria.fr/docs/00/55/55/88/PDF/techreport.pdf 

Briefly, the idea is pretty simple: each replica of the counter has an array of values, containing
one value per replica, called a payload. Each value in the array is the sum of the increments
that a single replica has performed. The value of the counter is the sum of the values in
the array. The payloads are sent to other replicas and each replica merges an incoming payload
by taking the maximum of each pair of values in the incoming and local arrays. This is idempotent
so payloads can be resent as many times as needed.
                
> Counters 2.0
> ------------
>
>                 Key: CASSANDRA-4775
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4775
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Arya Goudarzi
>            Assignee: Aleksey Yeschenko
>              Labels: counters
>             Fix For: 2.1
>
>
> The existing partitioned counters remain a source of frustration for most users almost
two years after being introduced.  The remaining problems are inherent in the design, not
something that can be fixed given enough time/eyeballs.
> Ideally a solution would give us
> - similar performance
> - less special cases in the code
> - potential for a retry mechanism

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