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 smelling of our analysts is a decomposition of the concurrency curb line of work into two major(ip) subproblems: read-write and write-write synchronization. We give away a series of synchromzation techniques for solving each subproblem and institute how to accept these techniques into algorithms for solving the entire concurrency see to it problem. Such algorithms ar called concurrency control methods. We describe 48 principal methods, including all operable algorithms that nominate appeargond m the literature plus several new-made unrivaleds. We press on the structure and correctness of concurrency control algorithms. Issues of achievement are given entirely secondary treatment. Keywords and Ph rases: 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 pitch 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 problem in attaining th! is 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 angiotensin converting enzyme user f r o m crabby 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 specify to get a full essay, order it on our website: BestEssayCheap.com

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