1. A computer-implemented system for facilitating cross-subsystem queries of a plurality of building automation subsystems, comprising: a first database storing a logical model for a building automation system; a second database storing information for the plurality of building automation subsystems, wherein the second database relates information for the plurality of building automation subsystems based on the logical model of the first database; and a query engine configured to decompose a cross-subsystem query received from an application into a plurality of subsystem queries using the information of the second database.