A method and system is presented for reaching consensus on adding data to and extending the structure or schema of databases synchronized across a distributed ledger or blockchain system, in which no central trusted authority is available, comprising sending an announcement message by a network connected device to a plurality of network connected devices over a network, said message proposing a database schema change or extension. If the announcement message and preceding data in the distributed ledger satisfy predetermined conditions, the plurality of network connected devices may include the data in the distributed ledger, and modify the schema of their databases in a corresponding manner. If data is submitted that requires a structural change to the database before the announcement message has been incorporated in the distributed ledger, the data is rejected by the network and is not included in the distributed ledger.