Ask HN: What data do alternative blockchains store?
Honest question. When someone says a blockchain can be used for anything OTHER than financial transactions, for example - supply chain, health records, etc - what is the actual underlying data that is being stored on the blockchain?
When it comes to a quasi-banking or quasi-wallet system, I find it easy to visualize that the blockchain holds accounts with balances, and there are transactions which move money between accounts. Blockchain's decentralization and write-only properties help because no single entity can make your money disappear, and no entity can rollback a transaction.
What is going on with other use-cases of blockchain? What does a supply-chain system actually store on the blockchain? The SKU list? The price of each SKU? The stock level of each SKU in each warehouse? What?
Further, how do the unique properties of a blockchain make it better than a centralised (or federated DB) for a SPECIFIC non-financial use-case (would appreciate actual details here)? Since a blockchain can only be used to verify activity on itself, blockchains are poor replacements for anything but markets. Anything being done that has access to an environment mutually trusted by all parties has no need of a blockchain - you just access a database in that environment. Moreover, there's no reason to run a blockchain on a trusted party - i.e. 'corporate' blockchains - for the same reason: since you already have to trust whoever is maintaining it, it can't verify anything new for you. The only reason these things exist is the large amounts of capital available to anyone who can shoehorn a blockchain into their business model. Blockchain has to be seen as a protocol is multiple layers. The transactions and ownership related data on stored on layer 0 or on chain. Anything to do with personal data or user data is stored on layer 1. Projects like Blockstack follows similar architecture. There are DApps available with non financial use-case. If we separate out the usefulness or profitability of using blockchains to store non financial data, Then The data type doesnt matter. Taking supply chains ( or asset tracking im general )
Transactions could be of the form From entity , To entity and Asset Descriptor - > mapped to blockchain ID From to asset timestamp hash
One could have functions like
Check_current_ownership()
Check_transferability() Ofcourse its difficult to keep onchain data and offchain data consistent.
So its best to have an adapter for real world data In other words, the blockchain is adding no value, at significant cost.