A study of the effects of locking granularity in a data base management system

ABSTRACT

Many data base systems guarantee some form of integrity control upon multiple concurrent updates by some form of locking. Some "granule" of the data base is chosen as the unit which is individually locked, and a lock management algorithm is used to ensure integrity. By a simulation model this paper explores the desired size of a "granule". Under a wide variety of seemingly realistic conditions, surprisingly coarse granularity is called for. The paper concludes with some implications of these results concerning the viability of so called "predicate locking".Research sponsored by the Naval Electronic Systems Command Contract N00039-76-c-0022, the National Science Foundation Grant DCR75-03839 and the Army Research Office Grant DAAG29-76-6-0245.