I'm not sure CRDTs are actually the right answer here for your example of #2, Marco. A double-entry accounting system might actually be more ideal. In that case, what you are keeping in sync is the ledger, but depending on your use-case, that might actually be easier since you can treat them as a stream-of-data, and you would get the 'correct' answer of 100.

In this case, you would need two accounts, a credit and debit account, and then device A would write +20 to the credit account and -20 to the debit account, device B would write -20 to the credit account and +20 to the debit account, then using a HLC (or even not, depending on what your use-case is again), you get back to the 100 that seems from the description of the problem that it is the correct answer.

Obviously, if you are editing texts there are very different needs, but this as described is right in the wheelhouse of double-entry accounting.

▲

michaelsalim 4 days ago | parent [-]

That's not what a double-entry accounting system is for. If all you're doing is keeping track of one account/balance, then double-entry doesn't add anything. You might want to still implement it that way for future proofing though if you're implementing an accounting system.

The main thing to takeway is to store transactions like you mentioned (+20, -20). And in the simplest case, just apply all of them based on time.

	▲	russnewcomer 3 days ago \| parent [-]
		You're not entirely wrong that double-entry accounting doesn't add much to keeping track of one balance. And the example provided in the article was very simple, just like mine was very simple. Transactions do help, but if you are trying to keep track of a balance and understanding how that balance is changing, double-entry accounting is helpful.