The middle part of 'CAP Twelve Years Later' [1], especially the part about 'Managing Partitions', and the associated diagram, really should be mandatory reading for anyone who invokes CAP, as it drives home the fact that a partition creates alternate universes (invariants), which have to be reconciled after the fact, and points out that allowing reads only is a valid strategy to provide Consistency (erroring out on writes), while systems that choose to provide Availability (trying to fulfill every transaction) will find themselves in a situation where they have to reconcile mutations that happened in separate universes, exactly like a version control system would. It also provides some strategies on how some write-like operations could be done to minimize disruption to existing state, such as recording the intent to mutate some data in a way that enables duplicates to be discarded later, and for the mutation to be performed at a time that it is safe.
The author of the HN-featured article is the formulator of the PACELC theorem, which makes clear that replication is mandatory and thus always propagates state that needs to be reconciled. The ability of nodes to freely communicate with one another means that it's possible to delay answers to operations until all nodes have recorded its effects. In the event of a partition, nodes cannot share information with other nodes, so a choice must be made between denying operations that would endanger states getting out of sync, or allowing them through, and dealing with the fallout later.
> recording the intent to mutate some data in a way that enables duplicates to be discarded later, and for the mutation to be performed at a time that it is safe.
Isn’t that, fundamentally, old school batch processing? Plus ça change, plus c’est le même chose...
"This is a good read" is a statement of opinion. You're free to assign whatever value you like to the op's opinion, but that opinion is "content" in and of itself.
"The article has false claim" is a statement of fact. A vague statement of fact about a non-obvious topic that puts no effort into providing concrete examples and reasoning is pretty much worthless.
Adding qualifiers makes a statement have less content? Please try to imagine using this questionable argument in any other context...
It's a controversial topic and TFA was written by someone with a commercial interest. Everything is opinion. The level of comment-policing I see here makes me quite suspicious of everything in TFA.
[EDIT:] aargh I'll never learn every discussion that starts with "content-free" cliche goes nowhere... just downvote and move on...
If you're suspicious about me, it's not very well-founded, considering my main comment thread on this story takes issue with the blog's claims: https://news.ycombinator.com/item?id=18039801
I just prefer to have discussions about specific things, not posturing and innuendo.
Too much is false to explain it, like half of the article. So I just called it out instead. I know it's not very convincing, but I'm not getting paid to write giant FUD/PR posts like they do. I work on distributed stuff completely independently.
