Block Pruning with UTXO Aggregation

The ledger of a blockchain is designed to be an append-only data structure, which means that its size only increases. Therefore, to run a node, it is a burden to the node operator to store the entire blockchain ledger. We propose a new method, UTXO aggregation, to reduce the high occupancy of storage. In this method, UTXOs are periodically merged, and a special block including all merged UTXOs is generated. Unlike Bitcoin's block file pruning, this method can allow other nodes to bootstrap and does not require a separate database that stores only UTXOs. This method also has the effect of reducing UTXOs with low economic value. By applying this method to Bitcoin, the storage occupancy of running a node can be immediately reduced to approximately 1/100, and an economic effect of up to 14120 BTC can be expected.