Abstract: Methods, systems, and computer program products for accessing data where the data store provider is abstracted from both the data manipulation language used to access the data and the schema that describes the data. A received request structured in accordance with the data manipulation language is represented in an intermediate form. From the intermediate representation, a native request for any of one or more data store providers may be produced. Before being returned to the requestor, a native response from data store provider may be formatted so that it is structured in accordance with the data manipulation language used for the request. A given request received by one computer system may cause a procedure to be generated for accessing the data store provider. When a later request is received by second computer system, the previously generated stored procedure may be reused if applicable.

Abstract: Methods, systems, and computer program products for converting a single expression referencing multiple branches within a hierarchical schema into multiple expressions referencing a single branch of the hierarchical schema. The single expression includes expression components that identify branches within the hierarchical schema. Relative to a given branch, any branches referenced by a given expression component are identified. The identified branches are stored as new branches. If no branch is identified, the current branch may be removed as inconsistent. Storage for current branches is cleared, the new branches are copied to the current branches, and the process is repeated for each expression component. An expression component may include a predicate for determining which branches are referenced. The predicate may include predicate expressions that are converted to predicate branches and the predicate may include predicate operators.