13. A computer system, comprising: a processor; and a computer-readable storage device storing instructions executed by the computer system cause the computer system to perform a method for displaying a data model, the instructions comprising: instructions for generating a model graph visualization to represent the data model and an instance graph visualization to represent an instance of the data model, wherein the data model includes entities which are related by relationships, wherein a vertex represents an entity in the model graph visualization or an entity instance in the instance graph visualization, and wherein an edge represents a relationship in the model graph visualization or a relationship instance in the instance graph visualization; instructions for concurrently displaying the model graph visualization and the instance graph visualization to a user, instructions for receiving a first request from the user to query a relationship between a first entity and a second entity in the data model, wherein the first request comprises selecting an edge in the displayed model graph visualization by the user; instructions, in response to the received first request, for determining paths in the displayed instance graph visualization between a first vertex which represents a first entity instance and a second vertex which represents a second entity instance, wherein each determined path in the displayed instance graph visualization represents an alternating sequence of entity instances and relationship instances in the instance of the data model; and instructions for displaying highlighting the determined paths in the displayed instance graph visualization to the user for exploring how the first entity and the second entity are related to one another in the data model.
13. A computer system, comprising: a processor; and a computer-readable storage device storing instructions executed by the computer system cause the computer system to perform a method for displaying a data model, the instructions comprising: instructions for generating a model graph visualization to represent the data model and an instance graph visualization to represent an instance of the data model, wherein the data model includes entities which are related by relationships, wherein a vertex represents an entity in the model graph visualization or an entity instance in the instance graph visualization, and wherein an edge represents a relationship in the model graph visualization or a relationship instance in the instance graph visualization; instructions for concurrently displaying the model graph visualization and the instance graph visualization to a user, instructions for receiving a first request from the user to query a relationship between a first entity and a second entity in the data model, wherein the first request comprises selecting an edge in the displayed model graph visualization by the user; instructions, in response to the received first request, for determining paths in the displayed instance graph visualization between a first vertex which represents a first entity instance and a second vertex which represents a second entity instance, wherein each determined path in the displayed instance graph visualization represents an alternating sequence of entity instances and relationship instances in the instance of the data model; and instructions for displaying highlighting the determined paths in the displayed instance graph visualization to the user for exploring how the first entity and the second entity are related to one another in the data model. 18. The computer system of claim 13 , wherein the instructions further comprises: instructions for receiving a third request from the user to highlight relationships whose names include a third search string; instructions for determining relationships in the data model whose names include the third search string; and instructions for highlighting edges in the displayed instance graph visualization which are associated with the determined relationships.