GraphDB : Modeling and Querying Graphs in Databases

Weproposeadatamodelandqueaylanguagethat integrates an explicit modeling and querying of graphssmoothlyintoastandsrddambaseenvimnment For standard applications, some hey featuresofobjectuientedmodeling~offesedsuchas object classes organized into a hierarchy, object identity, and attributes referencing objects. Queryingcanbedoneinafamiliarstylewitha &rive statement that can be used like a select . ..from . . . wkre.Gntheotherhand,themodel allows for an explicit mpresentation of graphs by partitioning object classes into simple classes, linkclasses,andpathclasseswhoseobjectscan be viewed as nodes, edges, and explicitly stored paths of a graph (which is the whole dambase ins-). For querying graphs, the derive statement has an extended meaning in that it allows onetoiefertosubgraphsofthedambasegraph.A powerful rewrite operation is offered for the manipulation of heterogeneous sequences of objects which often occur as a result of accessing thedambasegraph.Additionallytherearespecial graphoperationslikedekmnn@a&ortestpath or a subgmph and the model is extensible by such operations. Besides being attractive for standard applications, the model permits a natural representation and sophisticated querying of nelworks, in parhk of spatially embedded networks like highways, public transpart, etc. This work was suppoxted by the ESPRIT Basic Resepch Project 6881 AMUSING Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from the Endowment. Proceedings of the 20th VLDB Conference Santiago, Chile, 1994