LevelDB is a key value store used to store blockchain information, there are others which are used by nodes.
But if one man has some UTXOs and has lost his password, then these UTXOs will be in the DB forever? If i have created a new tx with the same txid that this man had, then my transaction won't be added to the blockchain ever?
If a pair of outputs are never spent, due to lost password or some other reason, they would remain on the data base as they are valid UTXOs.
You cannot just create another tx with a UTXO that you do not own, the nodes would verify and reject the transaction.
- Jay -