1. A method implemented by data processing apparatus, the method comprising: identifying one or more rows in a relational database that have each been modified since a first point in time, wherein each of the rows is associated with a respective table in the relational database; for each of the identified rows, updating a respective file in an external representation of the table associated with the row to reflect the modification to the row wherein the respective file is not stored in the database; and creating a first version of the relational database in a version control system using the external representation including one or more of the updated files, wherein the first version of the database comprises one or more files in the version control system.