> > I think implementation has to work according to expectations described in > CEP, and have enough tests to prove it. You can follow the progress of the > patch whenever CEP is accepted and code is published to learn about the > details. >
Thanks, will follow the implementation. If you'd like to learn more about incomplete Paxos writes (I'm assuming you > mean dealing with inability of proposer to collect a second quorum), you > can refer to Cassandra Paxos implementation. In our prototypes, we were > able to simply use Cassandra Paxos out of the box, and everything related > to Paxos is hidden from us behind CQL syntax. > Yes, it's the inability of the proposer to collect a second quorum. As I understand the existing LWT Paxos implementation is per key instance of Paxos. Being a key-value setup, it can always repair incomplete paxos runs when the key is read, For immutable log entries for CMS, it needs to be different. (LWT is also expecting a mutable operation on key. So it requires resetting of paxos state on commit and handling committed values separately as part of prepare. For immutable entries, that's not required). But will wait for the Jira and PR to understand the proposed approach better. Thanks, Unmesh > On Thu, Sep 1, 2022, at 11:08 AM, Unmesh Joshi wrote: > > On Thu, Sep 1, 2022 at 11:20 AM Alex Petrov <al...@coffeenco.de> wrote: > > > There will be no changes required to our existing Paxos implementation. We > can just use it. Besides, Paxos is only used as K-sequencer. There is no > need to use Raft, and both existing LWTs (with Multi-Paxos) and Accord > aren't tied to a single leader, which is well in the spirit of Cassandra. > > > Will the CMS log implementation be documented in another CEP? There are > subtle things like dealing with uncommitted incomplete writes or > propagating committed log entries to all the CMS replicas while deciding > how to maintain commit-index for the log will be a good detail to add? > The LWT Paxos implementation does this for the per key instance of Paxos > when a new Paxos read/write triggered (with special handling of committed > values). > > Thanks, > Unmesh > > >
