TYPE INFERENCE FOR DATALOG WITH COMPLEX TYPE HIERARCHIES

摘要

What is disclosed are a novel system and method for inferring types of database queries. In one embodiment a program and associated database schema that includes a type hierarchy is accessed. The program includes query operations to a database that contains relations described by a database schema. Types are inferred from definitions in the program by replacing each database relationship in the program by the types in the database schema. A new program is generated with the types that have been inferred with the new program only accessing unary relations in the database. In another embodiment, testing of each of the types that have been inferred is performed for type emptiness. In response to type emptiness being found for a type that have been inferred, a variety of different operations are performing including removing the type, providing a notification regarding the emptiness found for the type, and more.