PRED-DF - a data flow based semantic concurrency control protocol for real-time main-memory database systems

In real-time systems, the use of databases is increasing. If the application is safety-critical, one must guarantee in advance, by suitable verification methods, that all deadlines hold in all possible cases of use. Predictability of the database´s concurrency control protocol is one of the most important prerequisites for this. However, most real-time concurrency control protocols are influenced by traditional database requirements. For hard real-time systems, they are usually unsuitable, because they are not predictable and they noticeably interfere with task scheduling. We present a new semantic concurrency control protocol called PRED-DF (PREDeclaration and Data Flow analysis) for main-memory real-time database systems. PRED-DF uses pre-declaration, is locking-based and generates serializable schedules. It uses additional knowledge gained from advance analysis of the application´s data flow to minimize blocking times. PRED-DF´s behavior is predictable and so the verification of real-time requirements is possible