Lehrgebiet Informationssysteme

FB Informatik

LG IS

AG DBIS

(C) AG DBIS

Concurrency Control in Nested Transactions with Enhanced Lock Modes for KBMSs

Fernando de Ferreira Rezende, Theo Härder

University of Kaiserslautern
P.O. Box 3049, 67653 Kaiserslautern, Germany
e-mail: haerder@informatik.uni-kl.de

Full paper (postscript version compressed by gzip)

Abstract:

Nested transactions (NTs) allow the decomposition of execution units and finer grained control over concurrency and recovery than conventional, flat transac tions. Due to their characteristics, they provide adequate control structures for modeling transactions in several different environments. In this paper, we concentrate on the use of NTs in Knowledge Base Management Systems (KBMSs). With respect to those systems, the allowance for knowledge sharing is an important emerging point, which is going to be imperative for the complete success of KBMSs in the market. Nevertheless, to allow for knowledge sharing, special lock modes must be employed to adequately control the concurrency in KBMSs. We present enhanced lock modes tailored to the KBMS environment, which capture the abstraction relationships' semantics. Additionally, we couple these lock modes to an NT model allowing for upward as well as controlled downward inheritance of locks. Finally, on one hand, our NT model allows for an effective exploitation of intra-transaction parallelism, on the other hand, our enhanced lock modes make feasible the exploitation of the inherent parallelism in a knowledge representation approach.

Published in Proc. of the 6th Int. Conf. on Database and Expert Systems Applications (DEXA'95), London, UK, 1995, pp. 604-613.