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Gary Dusbabek commented on CASSANDRA-1391: ------------------------------------------ Bottom line: we need to solve the problem of how to handle conflicts. I view this as a similar problem of handling merge conflicts in change sets: a good subset of the conflicts can be merged automatically because they are independent of each other. But every once a while there is a conflict that needs a manual edit-the solution is not computable because it isn't deterministic. This is currently addressed right now by strictly enforcing the relationship of a migration with its predecessor to ensure that all migrations are applied serially. There is probably a pragmatic approach that I'm able to see because the merge-conflict problem makes it a non-starter for me. > Allow Concurrent Schema Migrations > ---------------------------------- > > Key: CASSANDRA-1391 > URL: https://issues.apache.org/jira/browse/CASSANDRA-1391 > Project: Cassandra > Issue Type: Improvement > Components: Core > Reporter: Stu Hood > Assignee: Gary Dusbabek > > CASSANDRA-1292 fixed multiple migrations started from the same node to > properly queue themselves, but it is still possible for migrations initiated > on different nodes to conflict and leave the cluster in a bad state. Since > the system_add/drop/rename methods are accessible directly from the client > API, they should be completely safe for concurrent use. > It should be possible to allow for most types of concurrent migrations by > converting the UUID schema ID into a VersionVectorClock (as provided by > CASSANDRA-580). -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira