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From Wayne Schroeder <wschroe...@pinsightmedia.com>
Subject Authoritative failed write: Using paxos to "cancel" failed quorum writes
Date Mon, 10 Mar 2014 20:29:05 GMT
As I understand it, even though a quorum write fails, the data is still (more than likely)
saved and will become eventually consistent through the well known mechanisms.  I have a case
where I would rather this not happen--where I would prefer that if the quorum write fails,
that data NEVER becomes consistent, and the old values remain.

After a bit of pondering, I came up the idea of simply making my write a conditional update
based on a previous value.  In my use case, I will not be contending with any other writes
of the same primary key, and this write operation is rare in the grand scheme of things. 
Using this approach, the desired effect is that if the write fails, it will not eventually
happen without the app's knowledge.

Is this approach sound?

If so, it sounds like a really cool potential addition to CQL like:  UPDATE tab SET col=?
WHERE key=? AUTHORITATIVE

Thoughts?

Wayne


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