A multi-structural query system performs a high-level multi-dimensional query on a multi-structural database. The query system enables a user to navigate a search by adding restrictions incrementally. The query system uses a schema to discover structure in a multi-structural database. The query system leaves a choice of nodes to return in response to a query as a constrained set of choices available to the algorithm. The query system further casts the selection of a set of nodes as an optimization. The query system uses pairwise-disjoint collections to capture a concise set of highlights of a data set within the allowed schema. The query system further comprises efficient algorithms that yield approximately optimal solutions for several classes of objective functions.