1. A system, comprising a plurality of computing devices configured to implement: a plurality of resources of a provider network; a plurality of data sources, wherein each data source of the plurality of data sources comprises records on a respective resource class of a plurality of resource classes, wherein each resource of the plurality of resources belongs to one or more resource classes of the plurality of resource classes; and a resource resolver; wherein the resource resolver is operable to: receive a request to identify a set of resources of the plurality of resources based on one or more criteria specified in the request; utilize a directed graph representation of at least a subset of the plurality of data sources to identify one or more query sequences to respond to the request, wherein the directed graph comprises a plurality of nodes and a plurality of edges, and wherein: each node of the directed graph represents a data source of the plurality of data sources, and each edge of the directed graph represents a logical relationship between the data sources whose nodes are connected by the edge; each edge of a set of edges of the directed graph has an associated weight based at least in part on a performance metric obtained from one of the two data sources whose nodes are connected by the edge; and each query sequence of the one or more query sequences comprises a plurality of queries, wherein each query of the plurality of queries is to be directed to a respective data source of the plurality of data sources; and issue one or more queries of a preferred query sequence identified from the one or more query sequences, wherein the one or more queries are issued to respective data sources of the plurality of data sources.