Sergey, +1 to your proposal. Looks pretty similar to Kafka's approach.
Ilya, >> Will they stay unsynced, or is there any mechanism of re-syncing? Yes, I'm currently working [1] on it. The current implementation allows restoring the latest value. [1] https://issues.apache.org/jira/browse/IGNITE-10663 On Thu, Apr 25, 2019 at 5:11 PM Ilya Kasnacheev <ilya.kasnach...@gmail.com> wrote: > Hello! > > When you have 2 backups and N = 1, how will conflicts be resolved? > > Imagine that you had N = 1, and primary node failed immediately after > operation. Now you have one backup that was updated synchronously and one > which did not. Will they stay unsynced, or is there any mechanism of > re-syncing? > > Why would one want to "update for 1 primary and 1 backup synchronously, > update the rest of backup partitions asynchronously"? What's the use case? > > Regards, > -- > Ilya Kasnacheev > > > чт, 25 апр. 2019 г. в 16:55, Sergey Kozlov <skoz...@gridgain.com>: > > > Igniters > > > > I'm working with the wide range of cache configurations and found (from > my > > standpoint) the interesting point for the discussion: > > > > Now we have following *writeSynchronizationMode *options: > > > > 1. *FULL_ASYNC* > > - primary partition updated asynchronously > > - backup partitions updated asynchronously > > 2. *PRIMARY_SYNC* > > - primary partition updated synchronously > > - backup partitions updated asynchronously > > 3. *FULL_SYNC* > > - primary partition updated synchronously > > - backup partitions updated synchronously > > > > The approach above is covering everything if you've 0 or 1 backup. > > But for 2 or more backups we can't reach the following case (something > > between *PRIMARY_SYNC *and *FULL_SYNC*): > > - update for 1 primary and 1 backup synchronously > > - update the rest of backup partitions asynchronously > > > > The idea is to join all current modes into single one and replace > > *writeSynchronizationMode > > *by the new option *syncPartitions=N* (not best name just for referring) > > covers the approach: > > > > - N = 0 means *FULL_ASYNC* > > - N = (backups+1) means *FULL_SYNC* > > - 0 < N < (backups+1) means either *PRIMARY_SYNC *(N=1) or new mode > > described above > > > > IMO it will allow to make more flexible and consistent configurations > > > > -- > > Sergey Kozlov > > GridGain Systems > > www.gridgain.com > > >
