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From "Aleksey Yeschenko (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4775) Counters 2.0
Date Wed, 12 Jun 2013 23:28:22 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4775?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13681748#comment-13681748
] 

Aleksey Yeschenko commented on CASSANDRA-4775:
----------------------------------------------

Was looking into possible variations of the original idea - the first comment in this issue,
and how we could implement it to allow true idempotent client-retriable counter updates, and
came with this so far: https://gist.github.com/iamaleksey/fa36552409dc2aa70bee

Cons:
- has significant overhead per-cell - needs to store the timeuuid in the column name
- has the obvious overhead of having multiple cells per single counter
- requires either forcing QUORUM writes (so that merge could get away with QUORUM reads) or
ALL reads for the merge. Now, this is probably true for any merge process for any variation
of 'each update = new cell, with periodic merges'
- requires special-casing on the read path
- maintaining backward compatibility isn't going to be fun

Pros:
- updates are truly idempotent (within the configurable write window)
- allows counters to coexist with regular columns in regular tables
- allows including counters in (non-logged) batches
- requires a lot less overall special-casing
- easily supports min/max/avg/sum_sq functions

Not sure if this is viable considering that '"retryable" is at the very bottom of my priorities
here' but maybe there is something useful in there anyway.
                
> 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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