It seems like the blockchain transactions only stores the number of coins moving from one wallet to the other, but does not have the total amounts for each wallet.
Therefore it seems like if you want to get the value of any given wallet you would have to read every transaction in the ledger from the very beginning.
Is this correct or am I missing something?
Fyi, my goal is to understand the format of the blockchain better
Assuming you don't trust anyone, you need to read the entire blockchain history once to generate your own set of unspent transactions (UTXOs). You won't need then to read again the full history every time you want to see your balance. Unspent Transactions are enough to do so.
Your balance is the sum of the values of the unspent transactions your wallet has. Unspent means here that you didn't "spend" the previously received amounts on outgoing transactions.
Example:
If it is your 'wallet' and you have the private keys then you can import them into a wallet application. The wallet, with some work, is able to decipher which addresses are yours, scan the transactions on the blockchain and, update the balances.
Therefore it seems like if you want to get the value of any given wallet you would have to read every transaction in the ledger from the very beginning.
Yes, basically. If you were sent 1 BTC in 2010 and never spent it, and 1 BTC in 2018 (also unspent), you have 2 BTC, but without going through the entire history of the ledger, you wouldn't be able to see both in your wallet without scanning the entire history.
It would be nice to be able to bootstrap a node with just the UTXO (unspent coins) at some point, but then to do this you'd have to trust the person generating the bootstrap, and you could not trace the true history of any of the coins (such as what IOTA do when they take a snapshot).
