A comparison of multi-level concurrency control protocols

Locking protocols for multi-level transactions have been studied since the very beginning. More recently, a hybrid concurrency control protocol for multi-level transactions called FoPL has been developed. It employs access lists on the database objects and forward oriented commit validation. The basic test on all levels is based on the reordering of the access lists. So far, a detailed analysis of FoPL´s benefits is missing. The paper describes a testbed for multi-level transactions which allows us to measure transaction throughput and rollback frequency. The testbed allows us to use a mix of strict two-phase locking and FoPL on up to 4 levels. The tests work on randomly generated multi-level transactions on the basis of pages, records and virtual database objects on higher levels