1. A method for identifying relationships among entity instances of a plurality of entities in a database, comprising: accessing, by a computing device, a plurality of entity reference relationship structures, each of the plurality of entity reference relationship structures comprising at least a pair of entity instance identifiers that identify a relationship between entity instances of a pair of entity structures of a plurality of entity structures; based on the plurality of entity reference relationship structures, determining, by the computing device, each complete graph among all subsets of the plurality of entity structures, wherein each complete graph comprises at least one edge corresponding to an entity reference relationship structure, and two vertices connected by the at least one edge that correspond to entity structures between which the entity reference relationship structure establishes a relationship; and for each complete graph: identifying, by the computing device, all matched sets of pairs of entity instance identifiers comprising a pair of entity instance identifiers from each entity reference relationship structure corresponding to the each complete graph; and storing the entity instance identifiers in each matched set in association with each other in an entity relationship structure.