In general, metadata is stored in a data storage system. Summary data identifying one or more characteristics of each of multiple metadata objects stored in the data storage system is computed, and the summary data characterizing a given metadata object in association with the given metadata object is stored. A visual representation is generated of a diagram including nodes representing respective metadata objects and relationships among the nodes. Generating the visual representation includes superimposing a representation of a characteristic identified by the summary data characterizing a given metadata object in proximity to the node representing the given metadata object.