Has anyone had a chance to read the drafts, and has any feedback or questions? Does anybody still anticipate doing so in the near future? Or shall we move to a vote?
From: bened...@apache.org <bened...@apache.org> Date: Tuesday, 7 September 2021 at 21:27 To: dev@cassandra.apache.org <dev@cassandra.apache.org> Subject: Re: [DISCUSS] CEP-15: General Purpose Transactions Hi Jake, > What structural changes are planned to support an external dependency project > like this To add to Blake’s answer, in case there’s some confusion over this, the proposal is to include this library within the Apache Cassandra project. So I wouldn’t think of it as an external dependency. This PMC and community will still have the usual oversight over direction and development, and APIs will be developed solely with the intention of their integration with Cassandra. > Will this effort eventually replace consistency levels in C*? I hope we’ll have some very related discussions around consistency levels in the coming months more generally, but I don’t think that is tightly coupled to this work. I agree with you both that we won’t want to perpetuate the problems you’ve highlighted though. Henrik: > I was referring to the property that Calvin transactions also need to be sent > to the cluster in a single shot Ah, yes. In that case I agree, and I tried to point to this direction in an earlier email, where I discussed the use of scripting languages (i.e. transactionally modifying the database with some subset of arbitrary computation). I think the JVM is particularly suited to offering quite powerful distributed transactions in this vein, and it will be interesting to see what we might develop in this direction in future. From: Jake Luciani <jak...@gmail.com> Date: Tuesday, 7 September 2021 at 19:27 To: dev@cassandra.apache.org <dev@cassandra.apache.org> Subject: Re: [DISCUSS] CEP-15: General Purpose Transactions Great thanks for the information On Tue, Sep 7, 2021 at 12:44 PM Blake Eggleston <beggles...@apple.com.invalid> wrote: > Hi Jake, > > > 1. Will this effort eventually replace consistency levels in C*? I ask > > because one of the shortcomings of our paxos today is > > it can be easily mixed with non serialized consistencies and therefore > > users commonly break consistency by for example reading at CL.ONE while > > also > > using LWTs. > > This will likely require CLs to be specified at the schema level for > tables using multi partition transactions. I’d expect this to be available > for other tables, but not required. > > > 2. What structural changes are planned to support an external dependency > > project like this? Are there some high level interfaces you expect the > > project to adhere to? > > There will be some interfaces that need to be implemented in C* to support > the library. You can find the current interfaces in the accord.api package, > but these were written to support some initial testing, and not intended > for integration into C* as is. Things are pretty fluid right now and will > be rewritten / refactored multiple times over the next few months. > > Thanks, > > Blake > > > > On Sun, Sep 5, 2021 at 10:33 AM bened...@apache.org <bened...@apache.org > > > > wrote: > > > >> Wiki: > >> > https://cwiki.apache.org/confluence/display/CASSANDRA/CEP-15%3A+General+Purpose+Transactions > >> Whitepaper: > >> > https://cwiki.apache.org/confluence/download/attachments/188744725/Accord.pdf > >> < > >> > https://cwiki.apache.org/confluence/download/attachments/188744725/Accord.pdf?version=1&modificationDate=1630847736966&api=v2 > >>> > >> Prototype: https://github.com/belliottsmith/accord > >> > >> Hi everyone, I’d like to propose this CEP for adoption by the community. > >> > >> Cassandra has benefitted from LWTs for many years, but application > >> developers that want to ensure consistency for complex operations must > >> either accept the scalability bottleneck of serializing all related > state > >> through a single partition, or layer a complex state machine on top of > the > >> database. These are sophisticated and costly activities that our users > >> should not be expected to undertake. Since distributed databases are > >> beginning to offer distributed transactions with fewer caveats, it is > past > >> time for Cassandra to do so as well. > >> > >> This CEP proposes the use of several novel techniques that build upon > >> research (that followed EPaxos) to deliver (non-interactive) general > >> purpose distributed transactions. The approach is outlined in the > wikipage > >> and in more detail in the linked whitepaper. Importantly, by adopting > this > >> approach we will be the _only_ distributed database to offer global, > >> scalable, strict serializable transactions in one wide area round-trip. > >> This would represent a significant improvement in the state of the art, > >> both in the academic literature and in commercial or open source > offerings. > >> > >> This work has been partially realised in a prototype. This partial > >> prototype has been verified against Jepsen.io’s Maelstrom library and > >> dedicated in-tree strict serializability verification tools, but much > work > >> remains for the work to be production capable and integrated into > Cassandra. > >> > >> I propose including the prototype in the project as a new source > >> repository, to be developed as a standalone library for integration into > >> Cassandra. I hope the community sees the important value proposition of > >> this proposal, and will adopt the CEP after this discussion, so that the > >> library and its integration into Cassandra can be developed in parallel > and > >> with the involvement of the wider community. > >> > > > > > > -- > > http://twitter.com/tjake > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@cassandra.apache.org > For additional commands, e-mail: dev-h...@cassandra.apache.org > > -- http://twitter.com/tjake
