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https://issues.apache.org/jira/browse/CASSANDRA-5062?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13593470#comment-13593470
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Cristian Opris commented on CASSANDRA-5062:
-------------------------------------------
So looking at your proposer algorithm where you do:
send(LEARN(C_new));
This can succeed on the lead replica (locally assuming you're using one of the
replicas as lead) but fail on all or some of the others.
The replica can happily continue with the next round even if a quorum has not
yet learned the previous round, leading to the situation
I'm describing
> Support CAS
> -----------
>
> Key: CASSANDRA-5062
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5062
> Project: Cassandra
> Issue Type: New Feature
> Components: API, Core
> Reporter: Jonathan Ellis
> Fix For: 2.0
>
> Attachments: half-baked commit 1.jpg, half-baked commit 2.jpg,
> half-baked commit 3.jpg
>
>
> "Strong" consistency is not enough to prevent race conditions. The classic
> example is user account creation: we want to ensure usernames are unique, so
> we only want to signal account creation success if nobody else has created
> the account yet. But naive read-then-write allows clients to race and both
> think they have a green light to create.
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