Re:CASPaxos: Linearizable Databases Without Logs
by rdtsc on Saturday January 25, 2020 @03:13AM
(#22145353)
CASPaxos has nice latency and recovery times on node failures and partition re-joins. The author of the algorithm has a comparison with other popular consistent distributed databases https://github.com/rystsov/perseus
I particularly like novelty of using a function closures which makes it elegant and approachable.
I also found the idea of the hierarchical ballots from the article pretty interesting. ([config ballot, range ballot, file ballot, register ballot]). And I suppose in the spirit of the original paper, it would be a nested set of closures :-)
One thing that might not be obvious though, compared to other databases, is that reads essentially follow the same path as the writes and cost about the same, and even might result in spreading the update to other nodes that don't have the latest value.
Re:CASPaxos: Linearizable Databases Without Logs
by jupp0r on Saturday January 25, 2020 @01:48AM
(#22145129)
> It is a slight modification of the original Paxos algorithm, which is very simple and typically used as a minimal building block for more complicated algorithms such as Multi-Paxos
Wasn't Raft invented as a teaching tool because Paxos was too hard to understand and implement correctly?
Re:CASPaxos: Linearizable Databases Without Logs
by uluyol on Saturday January 25, 2020 @04:37AM
(#22145567)
Personally, and I have heard many other people say this as well, I don't think Raft is any simpler than Paxos.
The problem with Paxos is that there is no one way to do things. There are a thousand different variants and techniques that are not all compatible with each other. So to actually implement Paxos essentially requires that you become an expert. The advantage of Paxos is that there are many potential optimizations at your fingertips, depending on your workload.
Unlike Paxos, Raft is much more prescriptive: do x, y, and z, and everything will be fine. And really, to a large extend, Raft can be viewed as a description of what many production Paxos implementations would look like.
https://vadosware.io/post/paxosmon-gotta-concensus-them-all
(lots of links to papers inside)
It's a fascinating field and there are a LOT of variations of Paxos worth investigating.
I recently added a ToC so that it's a little easier to navigate/jump around
Edit: it's https://arxiv.org/pdf/1802.07000.pdf
I particularly like novelty of using a function closures which makes it elegant and approachable.
I also found the idea of the hierarchical ballots from the article pretty interesting. ([config ballot, range ballot, file ballot, register ballot]). And I suppose in the spirit of the original paper, it would be a nested set of closures :-)
One thing that might not be obvious though, compared to other databases, is that reads essentially follow the same path as the writes and cost about the same, and even might result in spreading the update to other nodes that don't have the latest value.
Wasn't Raft invented as a teaching tool because Paxos was too hard to understand and implement correctly?
The problem with Paxos is that there is no one way to do things. There are a thousand different variants and techniques that are not all compatible with each other. So to actually implement Paxos essentially requires that you become an expert. The advantage of Paxos is that there are many potential optimizations at your fingertips, depending on your workload.
Unlike Paxos, Raft is much more prescriptive: do x, y, and z, and everything will be fine. And really, to a large extend, Raft can be viewed as a description of what many production Paxos implementations would look like.
Madman, cult, or both?