The Notions of Consistency and Predicate Locks in a Database System In database systems, users access shared data under the assumption that the data satisfies certain consistency constraints. This paper defines the concepts of transaction, consistency and schedule and shows that consistency requires that a transaction cannot request new locks after releasing a lock. Then it is argued that a transaction needs to lock a logical rather than a physical subset of the database. These subsets may be specified by predicates. An implementation of predicate locks which satisfies the consistency condition is suggested. CACM November, 1976 Eswarran, K.. Gray, J.. Lorie, R.. Traiger, I. L. consistency, lock, database, concurrency, transaction 4.32 4.33 CA761106 JB January 3, 1978 3:14 PM 2155 4 2817 2406 4 2817 2710 4 2817 2715 4 2817 2716 4 2817 2717 4 2817 2718 4 2817 2765 4 2817 2817 4 2817 2888 4 2817 2901 4 2817 2957 4 2817 2959 4 2817 2965 4 2817 3087 4 2817 3154 4 2817 2046 5 2817 2817 5 2817 2817 5 2817 2817 5 2817 3148 5 2817 1860 6 2817 2817 6 2817 2865 6 2817 2939 6 2817 3073 6 2817