Hi, the analysis is valid, and strong consistency the Cassandra way means that one client writing at quorum, then reading at quorum will always see his previous write. Two different clients have no guarantee to see the same data when using quorum, as illustrated in your example.
Only options here are to route requests to specific clients based on some id to guarantee the sequence of operations outside of Cassandra (the same client will always be responsible for a set of ids), or raise the CL to ALL at the expense of availability (you should not do that). Cheers, Alex Le mer. 14 sept. 2016 à 11:47, Qi Li <ken.l...@gmail.com> a écrit : > hi all, > > we are using quorum consistency, and we *suspect* there may be a race > condition during the write. lets say RF is 3. so write will wait for at > least 2 nodes to ack. suppose there is only 1 node acked(node A). the other > 2 nodes(node B, C) are still waiting to update. there come two read requests > one read is having the data responded from the node B and C, so version 1 > us returned. > the other node is having data responded from node A and B, so the latest > version 2 is returned. > > so clients are getting different data at the same time. is this a valid > analysis? if so, is there any options we can set to deal with this issue? > > thanks > Ken >
