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https://issues.apache.org/jira/browse/CASSANDRA-1072?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12899112#action_12899112
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Jeff Darcy commented on CASSANDRA-1072:
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If I'm reading this correctly, then the prior approach would have required
reading at CL.ALL to get a consistent result and this reduces it to CL.QUORUM
instead. At least, that's the only way I can reconcile "lift
some of (what I believe to be) the main limitation" from August 10 with both
"handling better network partitions" and "exact same behavior and consistency"
today. Is that correct? If it is, let's look at the simultaneous-write case
some more. Let's say two nodes get updates at the exact same instant, both at
CL.QUORUM. A reader at CL.QUORUM will therefore see at least one value
reflecting each of those updates. If that reader does see inconsistent values,
how will it reconcile them? In particular, if it sees A=10/B=11/C=12 from
three replicas, how will it distinguish between the following?
(a) Initial value was 10, B got a +1 which hasn't propagated, C got a +2 which
hasn't propagated -> reconciliation should yield 13.
(b) Initial value was 10, B got a +1 which propagated to C but not A, C got a
+1 which hasn't propagated at all -> reconciliation should yield 12.
I'm not trying to poke holes here; I'm just curious because I don't see clearly
how the scheme you laid out would handle this case.
> Increment counters
> ------------------
>
> Key: CASSANDRA-1072
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1072
> Project: Cassandra
> Issue Type: Sub-task
> Components: Core
> Reporter: Johan Oskarsson
> Assignee: Kelvin Kakugawa
> Attachments: CASSANDRA-1072-2.patch, CASSANDRA-1072.patch,
> Incrementcountersdesigndoc.pdf
>
>
> Break out the increment counters out of CASSANDRA-580. Classes are shared
> between the two features but without the plain version vector code the
> changeset becomes smaller and more manageable.
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