Database

Concurrency Control in Distributed Database Systems PHILIP A. BERNSTEIN AND NATHAN GOODMAN Computer Corporation of America, Cambridge, Massachusetts 02139 In this paper we survey, consolidate, and present the state of the art in distributed database concurrency image. The face of our analysts is a decomposition of the concurrency direct fuss into two major(ip) subproblems: read-write and write-write synchronization. We line a series of synchromzation techniques for solving each subproblem and institute how to unify these techniques into algorithms for solving the entire concurrency obligate problem. Such algorithms ar called concurrency control methods. We describe 48 principal methods, including all operable algorithms that create appe ard m the literature plus several new-made unrivaleds. We turn on the structure and correctness of concurrency control algorithms. Issues of achievement are given nevertheless secondary treatment. Keywords and Phrases: concurrency control, deadlock, dtstnbuted database management systems, locking, senahzability, synchromzation, tunestamp ordering, timestamps, twophase commit, two-phase locking CR Categories: 4.33, 4.

35 INTRODUCTION The Concurrency Control Problem C o n c u r r e n c y control is the activity of lay out concurrent accesses to a database in a multiuser d a t a b a s e m a n a g e m e n t s y s t e m (DBMS). C o n c u r r e n c y control permits users to access a d a t a b a s e in a multip r o g r a m m e d fashion while preserving the illusion t h a t each user is executing only if on a dedicated system. T h e m a i n technical prob lem in attaining this goal is to p r e v e n! t d a t a b a s e u p d a t e s p e r f o r m e d b y wiz user f r o m special with d a t a b a s e retrievals and u p d a t e s p e r f o r m e d b y another. T h e concurrency control p r o b l e m is e x a c e r b a t e d in a distributed D B M S ( D D B M S ) because (1) users m a y access d a t a stored in m a n y different c o m p u...If you peck to get a full essay, order it on our website: OrderCustomPaper.com

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