IMO, the main concern of C*'s counter is, it is not idempotent. For example, if you add a counter and get a timeout error, you can not know whether it is successful. For non-counter writes, they are idempotent so you can just retry, but if you retry in counter, there may be a double write.
2015-06-23 12:23 GMT+08:00 Mike Trienis <mike.trie...@orcsol.com>: > > Hi All, > > I'm fairly new to Cassandra and am planning on using it as a datastore for > an Apache Spark cluster. > > The use case is fairly simple, read the raw data and perform aggregates > and push the rolled up data back to Cassandra. The data models will use > counters pretty heavily so I'd like to understand what kind of accuracy > should I expect from Cassandra 2.1 when increment the counters. > > - > > http://www.datastax.com/dev/blog/whats-new-in-cassandra-2-1-a-better-implementation-of-counters > > The blog post above states that the new counter implementations are > "safer" although I'm not sure what that means in practice. Will the > counters be 99.99% accurate? How often will they be over or under counted? > > Thanks, Mike. > -- Thanks, Phil Yang
