A relational database system may receive from a client a query that is supported by the relational database system, the relational database system being configured to store a plurality of data objects such that each data object is associated with a respective data table of a plurality of data tables. The system may determine that the query is indicative of a data object type that is associated with data stored in a data system separate from the relational database system. The system may identify a schema of the data object type using a schema record maintained by the relational database system, transmit to the separate data system a request for data associated with the query, receive requested data, and return a query response including the requested data.