Effects of Locking Granularity in a Database Management System

Abstract

Many database systems guarantee some form of integrity control upon multiple concurrent updates by some form of locking. Some “granule” of the database is chosen as the unit which is individually locked, and a lock management algorithm is used to ensure integrity. Using 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”. © 1977, ACM. All rights reserved. © 1977, ACM. All rights reserved.