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From "Cristian Opris (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-5062) Support CAS
Date Mon, 25 Feb 2013 22:44:15 GMT


Cristian Opris commented on CASSANDRA-5062:

So I guess what I'm proposing is similar to what Piotr said above: each CAS is a round of
With some cleverness this can be collapsed to Multi-Paxos. 

Spinnaker does leader election with ZK precisely because they did not want to implement Paxos

>From the paper, section 5: "The replication protocol has two phases: a leader election
phase, followed by a quorum phase where the leader proposes a write and the followers accept

That is Multi-Paxos, with first phase (leader election) handled by ZK and second phase being
the steady state (propose/accept) with the actual write/commit
> Support CAS
> -----------
>                 Key: CASSANDRA-5062
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>             Fix For: 2.0
> "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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