The notions of consistency and predicate locks in a database system
Authors:
Open Access
- 1 November 1976
- journal article
- Published by Association for Computing Machinery (ACM) in Communications of the ACM
- Vol. 19 (11) , 624-633
Abstract
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.Keywords
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