> The only way to guard against that risk is to replicate and publicize the data, make sure all data modifications are cryptographically signed and valid according the logic of the application, and incorporate into each new version of the data a hash of prior versions of the data, in order to guard against data deletions. In other words, to implement a blockchain.
nothing you’ve described here requires the decentralized parts of a blockchain. there exist centralized databases that have all of these properties, and people have mentioned them in the comments.
You are quibbling with semantics. What you have quoted is the definition of a blockchain. Any "centralized" database with these properties is a blockchain, for all intents and purposes.
A system with all those properties is a git repository containing all this data. Which would also scale to more operations per second than a block chain, is much more battle-hardened than any blockchain...
And decidedly isn't a blockchain. It's just a merkle tree that can easily be replicated / updated via "git clone" / "git fetch".
Your definition of a blockchain seems to be different than what most people use, though I admit a lot of blockchain advocates seem to make the definition tighter or looser depending on which is more convenient for the current argument.
Your comment makes me believe that you don't think very highly of "blockchain advocates". But you don't seem to have much of a problem with using a replicated git repository in this manner.
So what is the specific problem that you have? You just don't like the fact that blockchain data mutations are bundled into periodically-generated blocks that incorporate changes from multiple users, rather than being pushed by individual users on an ad hoc basis? Is it a problem for you that blockchain nodes maintain network connections with each other, and have a protocol for ensuring that they all remain in sync, rather than relying on individual users to pull and manually merge changes explicitly?
A typical feature of religious disputes is that the smallest distinction takes on the most momentous significance. Is that not what's going on here?
You're right that this level of pedantry isn't actually that useful. However, we're both on hacker news and thus presumably steeped in technology, which seems to turn people into pedants quite easily. I'm making the pedantic point because you're already talking specifically about tiny semantic points in this thread, and if you're going to quibble semantics, pedantry seems open.
This distinction is not the one that actually matters and does not have huge significance in my frustration with blockchain advocates.
To me, the large issue seems to be that people advocating for blockchain _stuff_ usually seem to be ignoring reality and trying to paint a libertarian dream that is simply entirely divorced from how real governments and societies currently function.
The exact definition of blockchain doesn't matter. The use of a blockchain technology also doesn't matter (like, I don't care if my doctor is saving my records in Oracle SQL, some private blockchain, or whatever, never have cared, as long as the data is still there next time my doctor needs it, and it's compliant with legal privacy requirements).
What matters is that "blockchain" always seems to be coupled with "and by using it, it will fix this social problem somehow" when that problem is inevitably social or political, not technical.
I'm all for fixing these problems, but switching databases ain't it when the problem is several layers off, so it seems like at best a distraction from useful action, and at worst a grift to extract money from various entities by promising an easy solution to a difficult problem, which cannot realistically be delivered on.
surveying definitions of blockchain, decentralized consensus is consistently a part of the definition. a blockchain without distributed consensus is something less specific.
i also don’t know why you put “centralized in quotes”. amazon qldb has all of the qualities you describe and is 100% centralized.
nothing you’ve described here requires the decentralized parts of a blockchain. there exist centralized databases that have all of these properties, and people have mentioned them in the comments.