Transaction Management with Integrity Checking

Database integrity constraints, understood as logical conditions that must hold for any database state, are not fully supported by current database technology. It is typically up to the database designer and application programmer to enforce integrity via triggers or tests at the application level, which are difficult to maintain and error prone. Two important aspects must be taken care of. 1. It is too time consuming to check integrity constraints from scratch after each update, so simplified checks before each update should be used relying on the assumption that the current state is consistent. 2. In concurrent database systems, besides the traditional correctness criterion, the execution schedule must ensure that the different transactions can overlap in time without destroying the consistency requirements tested by other, concurrent transactions. We show in this paper how to apply a method for incremental integrity checking to automatically extend update transactions with locks and simplified consistency tests on the locked elements. All schedules produced in this way are conflict serializable and preserve consistency in an optimized way.