Blockchain-based hierarchical data storage

A system comprising:

• one or more computers, and
• one or more non-transitory, machine-readable media storing one or more instructions that, when executed by the one or more computers, perform operations comprising:
• determining, based on a blockchain stored in a database, a block number interval that includes one or more block numbers associated with data nodes to be migrated to a lower level of storage, wherein each of the data nodes is included in a state Merkle tree and is associated with a block number of a block of the blockchain where a corresponding data node was last updated;
• determining, based at least on a right endpoint value of the block number interval, a migration threshold that is greater than any of the one or more block numbers included in the block number interval, wherein the migration threshold is a block number of a target block of the blockchain;
• traversing a state Merkle tree corresponding to the target block to identify first one or more target data nodes associated with block numbers smaller than the migration threshold;
• changing the block numbers associated with the first one or more target data nodes to the migration threshold;
• traversing one or more state Merkle trees corresponding to one or more blocks of the blockchain with the one or more block numbers in the block number interval to identify second one or more target data nodes associated with block numbers smaller than the migration threshold;
• and
• migrating the second one or more target data nodes to the lower level of storage.

A non-transitory, computer-readable medium storing one or more instructions executable by a computer system to perform operations comprising:

• determining, based on a blockchain stored in a database, a block number interval that includes one or more block numbers associated with data nodes to be migrated to a lower level of storage, wherein each of the data nodes is included in a state Merkle tree and is associated with a block number of a block of the blockchain where a corresponding data node was last updated;
• determining, based at least on a right endpoint value of the block number interval, a migration threshold that is greater than any of the one or more block numbers included in the block number interval, wherein the migration threshold is a block number of a target block of the blockchain;
• traversing a state Merkle tree corresponding to the target block to identify first one or more target data nodes associated with block numbers smaller than the migration threshold;
• changing the block numbers associated with the first one or more target data nodes to the migration threshold;
• traversing one or more state Merkle trees corresponding to one or more blocks of the blockchain with the one or more block numbers in the block number interval to identify second one or more target data nodes associated with block numbers smaller than the migration threshold;
• and
• migrating the second one or more target data nodes to the lower level of storage.