A computer-implemented method can receive a source table containing data tuples and a source schema defining attributes of the data tuples, and match the source schema to an ontology of a knowledge graph. The knowledge graph can include a plurality of instances and the ontology defines properties of the plurality of instances. The computer-implemented method can link the data tuples to respective instances in the knowledge graph, and identifying non-matching properties of the respective instances, wherein the non-matching properties are defined in the ontology and not matched to the source schema. The computer-implemented method can obtain property values associated with the non-matching properties from the knowledge graph, and add one or more of the non-matching properties and the associated property values to respective data tuples of the source table.