Great! Thank you for these details. I have to say your CEP is very thorough and a lot of effort went into it which I definitely appreciate.
Regards On Tue, Mar 10, 2026 at 1:40 PM Alex Petrov <[email protected]> wrote: > > 1) according to the section called "Project plan", you have divided > this into "phases". What "phase" this CEP is considered to be > production-ready and what Cassandra release do you plan to do it in? > > > Each phase can be an independent deliverable, and our intention is to keep > committing them to trunk and making them available right away. Of course, we > can keep it all in a feature branch and keep rebasing it, but I do not see a > good reason to do that. In cases where multiple patches would constitute a > logical addition, we will make sure to keep them in a feature branch and > commit together. > > 2) What is the risk of you abandoning this CEP in the middle? > > > I cannot recall any precedent for CEPs being abandoned, particularly > recently, and I do not see any risk of that. > > There has always been a push for delivering CEPs in smaller increments from > the community, and this is what we're intending to do here. Each commit is an > independent improvement. Even if work were to be stopped midway, we would > simply get a bunch of improvements. But I do not see any risk of stopping > midway. > > 3) You are using the language in your CEP as "we will do", "we will > allow". Who exactly is "we" in this case? Is this CEP going to be a > one-man show only and if not, who is going to work on this? Maybe a > silly question, but I am just genuinely interested in knowing who is > going to be dealing with this. > > > I cannot recall any other CEP getting a question about resourcing, and > unfortunately I cannot go into details of resourcing. Main goal of a CEP is > to socialize a high-level design, which I believe we have done here. > > Regarding timelines, the best answer is "between 6.0 and 7.0". I will do my > best to keep the community with timeline updates and changes. If anyone has > questions about progress at any time during the project, I will be happy to > address them and give updates. > > This CEP seems to be pretty complicated, from a high-level point of view at > least. I think the > relative lack of the questions you received on this CEP might mean > that people just do not know what to ask. > > > Good news is that I already have a working proof-of-concept, which is why I > was able to go deep into a lot of detail. I see no risk of delivery, > especially given the heaviest lifting was done by TCM. I did my best to > evaluate all potential risks while writing a CEP, and I currently do not see > any big unknowns. > > --Alex > > On Tue, Mar 10, 2026, at 9:35 AM, Štefan Miklošovič wrote: > > Hi Alex, > > 1) according to the section called "Project plan", you have divided > this into "phases". What "phase" this CEP is considered to be > production-ready and what Cassandra release do you plan to do it in? > > 2) What is the risk of you abandoning this CEP in the middle? > > 3) You are using the language in your CEP as "we will do", "we will > allow". Who exactly is "we" in this case? Is this CEP going to be a > one-man show only and if not, who is going to work on this? Maybe a > silly question, but I am just genuinely interested in knowing who is > going to be dealing with this. This CEP seems to be pretty > complicated, from a high-level point of view at least. I think the > relative lack of the questions you received on this CEP might mean > that people just do not know what to ask. > > 4) Do you also plan to document what you did so we present this CEP to > users in some digestible way or are they supposed to read the source > code and your CEP only in order to be productive? > > Regards > > On Tue, Feb 24, 2026 at 9:18 AM Alex Petrov <[email protected]> wrote: > > > > Hi everyone, > > > > We'd like to propose CEP-60: Flexible Placements [1] for adoption by the > > community. Building on CEP-21's Transactional Cluster Metadata [2], CEP-60 > > enables incremental, resumable operations, improved cluster density, and > > flexibility of data placements / ownership. > > > > CEP-60 benefits all users by further improving reliability of ownership > > operations. With flexible placements, clusters maintain near-optimal load > > balance at any size without explicit rebalancing phases. Ownership changes > > are broken into smaller sub-range steps that benefit from zero-copy > > streaming. > > > > CEP-60 is designed for incremental delivery: range-aware compaction, > > routing key abstractions, and metrics collection are useful on their own > > and will ship independently of the flexible placements feature. Existing > > token-based and vnode clusters will continue to work (while benefitting > > from incremental ops), and flexible placements can be enabled (and later > > disabled, if ever needed) on a per-keyspace basis. > > > > The CEP is linked here: > > https://cwiki.apache.org/confluence/display/CASSANDRA/CEP-60:+Flexible+Placements > > > > Looking forward to the discussion of this CEP here on the dev list. > > > > Thanks! > > > > [1] > > https://cwiki.apache.org/confluence/display/CASSANDRA/CEP-60:+Flexible+Placements > > [2] > > https://cwiki.apache.org/confluence/display/CASSANDRA/CEP-21%3A+Transactional+Cluster+Metadata > >
