On being optimistic about real-time constraints

Jayant R. Haritsa, Michael J. Carey, Miron Livny
1990 Proceedings of the ninth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems - PODS '90  
Performance studies of concurrency control algorithms for conventional database systems have shown that, under most operating circumstances, locking protocols outperform optimistic techniques. Real-time database systems have special characteristics -timing constraints are associated with transactions, performance criteria are based on satisfaction of these timing constraints, and scheduling algorithms are priority driven. In light of these special characteristics, results regarding the
more » ... ce of concurrency control algorithms need to be re-evaluated. We show in this paper that the following parameters of the real-time database system -its policy for dealing with transactions whose constraints are not met, its lolowledge of transaction resource requirements, and the availability of resourceshave a significant impact on the relative performance of the concurrency control algorithms. In particular, we demonstrate that under a policy that discards transactions whose constraints are not met, optimistic concurrency control outperforms locking over a wide range of system utilization. We also outline why, for a variety of reasons, optimistic algorithms appear well-suited to real-time database systems. ' We assume here that serializubili?y [Eswa76] is the required level of database correctness.
doi:10.1145/298514.298585 dblp:conf/pods/HaritsaCL90 fatcat:rvphujoq5ncatf5gkxeuylspci