An example operation may include one or more of receiving, by a data store peer, measured values of objects, storing, by the data store peer, the measured values along with corresponding hash/time pair values on a data store of the data store peer, executing, by the data store peer, a smart contract to update the hash/time pair values on a blockchain ledger, executing, by the data store peer, a smart contract to retrieve hash values corresponding to a particular time from the blockchain ledger and providing the hash values to the data store, generating, by the data store peer, a summary table that contains object values retrieved from the data store based on the hash values, and executing, by the data store peer, a smart contract to calculate a fee based on the summary table.