A computer-implemented method comprising: at a service platform, receiving a first document related to an order, wherein the first document is for requesting custom clearance for merchandize included in the order, and wherein the first document comprises mutable data and immutable data; at the service platform, adding index data to the first document to link the mutable data with the immutable data, wherein the index data include a transaction hash associated with a transaction related to the first document, wherein the transaction hash is a hash value of the immutable data; at the service platform, encrypting the immutable data to generate encrypted first data for storing in a blockchain database on a blockchain; sending the encrypted first data and the index data to the blockchain to store the encrypted first data and the index data on the blockchain in the blockchain database as managed by a blockchain network, wherein the encrypted first data are stored on the blockchain through consensus of blockchain nodes of a blockchain network; and storing the mutable data and the index data in a smart contract cache storage of the blockchain, wherein the cache storage is for storage of mutable data managed by smart contracts, wherein the smart contract cache storage is a storage medium with a faster read and write speed compared to a read and write speed of the blockchain database, wherein the index data stored at the smart contract cache storage is for associating the mutable data stored at the smart contract cache storage and the immutable data at the blockchain database as associated with the same transaction. at a service platform, receiving a first document related to an order, wherein the first document is for requesting custom clearance for merchandize included in the order, and wherein the first document comprises mutable data and immutable data; at the service platform, adding index data to the first document to link the mutable data with the immutable data, wherein the index data include a transaction hash associated with a transaction related to the first document, wherein the transaction hash is a hash value of the immutable data; at the service platform, encrypting the immutable data to generate encrypted first data for storing in a blockchain database on a blockchain; sending the encrypted first data and the index data to the blockchain to store the encrypted first data and the index data on the blockchain in the blockchain database as managed by a blockchain network, wherein the encrypted first data are stored on the blockchain through consensus of blockchain nodes of a blockchain network; and storing the mutable data and the index data in a smart contract cache storage of the blockchain, wherein the cache storage is for storage of mutable data managed by smart contracts, wherein the smart contract cache storage is a storage medium with a faster read and write speed compared to a read and write speed of the blockchain database, wherein the index data stored at the smart contract cache storage is for associating the mutable data stored at the smart contract cache storage and the immutable data at the blockchain database as associated with the same transaction.