11. An apparatus, comprising: one or more processors; memory; and a program module, wherein the program module is stored in the memory and, during operation of the apparatus, is executed by the one or more processors to request desired information from a graph database storing a graph, the program module including: instructions for receiving an initial query that is compatible with a first type of database that is different from the graph database; instructions for converting the initial query into a query using primitives, wherein the primitives comprise: a rule, based on edges in the graph, that expresses a relational schema in the first type of database, and information associated with a compound key that specifies a relationship between nodes, edges and predicates in the graph corresponding to a table in the first type of database; instructions for executing the query against the graph database, wherein: the graph comprises nodes, edges between the nodes, and predicates to represent and store data with index-free adjacency; and the query identifies a first edge associated with a predicate that specifies one or more of the nodes in the graph; and instructions for receiving a result in response to the query, wherein the result includes a subset of the graph.
11. An apparatus, comprising: one or more processors; memory; and a program module, wherein the program module is stored in the memory and, during operation of the apparatus, is executed by the one or more processors to request desired information from a graph database storing a graph, the program module including: instructions for receiving an initial query that is compatible with a first type of database that is different from the graph database; instructions for converting the initial query into a query using primitives, wherein the primitives comprise: a rule, based on edges in the graph, that expresses a relational schema in the first type of database, and information associated with a compound key that specifies a relationship between nodes, edges and predicates in the graph corresponding to a table in the first type of database; instructions for executing the query against the graph database, wherein: the graph comprises nodes, edges between the nodes, and predicates to represent and store data with index-free adjacency; and the query identifies a first edge associated with a predicate that specifies one or more of the nodes in the graph; and instructions for receiving a result in response to the query, wherein the result includes a subset of the graph. 15. The apparatus of claim 11 , wherein the subset of the graph includes the desired information expressed within an associated structure of the graph.