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From Kenny Yu <kenny...@knewton.com>
Subject Counter consistency - are counters idempotent?
Date Fri, 22 Jul 2011 14:52:21 GMT
As of Cassandra 0.8.1, are counter increments and decrements idempotent? If,
for example, a client sends an increment request and the increment occurs,
but the network subsequently fails and reports a failure to the client, will
Cassandra retry the increment (thus leading to an overcount and inconsistent
data)?

I have done some reading and I am getting conflicting sources about counter
consistency. In this source (
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/clarification-of-the-consistency-guarantees-of-Counters-td6421010.html),
it states that counters now have the same consistency as regular
columns--does this imply that the above example will not lead to an
overcount?

If counters are not idempotent, are there examples of effective uses of
counters that will prevent inconsistent counts?

Thank you for your help.

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