2/3 attack. Read up on BFT.

It doesn't matter, it's a dumb idea anyway because there is a central authority managing the land registry and there is no need for anyone else to be involved.

Also, SQL database is much more convenient to use, it has query language and indices unlike a blockchain.

	▲	c7b 21 hours ago \| parent [-]
		You can put an index on your blockchain DB, what are you talking? Every node can manage it as it pleases (within the limits of the consensus algorithm). Yes, if you have a centralized model you don't need it. Just saying that this incident is the exact risk a blockchain is meant to mitigate through redundancy. You can say you don't care about this risk, but it doesn't change the truth of the statement.