Thanks Aaron. I've mitigated this by removing the dependency on idempotent counters. But its good to know the limitations of counters.
Thanks Jabbar Azam On 19 May 2014 08:36, "Aaron Morton" <aa...@thelastpickle.com> wrote: > Does anybody else use another technique for achieving this idempotency > with counters? > > > The idempotency problem with counters has to do with what will happen when > you get a timeout. If you reply the write there is a chance of the > increment been applied twice. This is inherent in the current design. > > Cheers > Aaron > > > ----------------- > Aaron Morton > New Zealand > @aaronmorton > > Co-Founder & Principal Consultant > Apache Cassandra Consulting > http://www.thelastpickle.com > > On 9/05/2014, at 1:07 am, Jabbar Azam <aja...@gmail.com> wrote: > > Hello, > > Do people use counters when they want to have idempotent operations in > cassandra? > > I have a use case for using a counter to check for a count of objects in a > partition. If the counter is more than some value then the data in the > partition is moved into two different partitions. I can't work out how to > do this splitting and recover if a problem happens during modification of > the counter. > > > http://www.ebaytechblog.com/2012/08/14/cassandra-data-modeling-best-practices-part-2explains > that counters shouldn't be used if you want idempotency. I would > agree, but the alternative is not very elegant. I would have to manully > count the objects in a partition and then move the data and repeat the > operation if something went wrong. > > It is less resource intensive to read a counter value to see if a > partition needs splitting then to read all the objects in a partition. The > counter value can be stored in its own table sorting in descending order of > the counter value. > > Does anybody else use another technique for achieving this idempotency > with counters? > > I'm using cassandra 2.0.7. > > > > Thanks > > Jabbar Azam > > >
