Replication, consistency, and practicality: are these mutually exclusive?

  • Authors:
  • Todd Anderson;Yuri Breitbart;Henry F. Korth;Avishai Wool

  • Affiliations:
  • Department of Computer Science, University of Kentucky, Lexington, KY;Bell Laboratories, Lucent Technologies Inc., 600 Mountain Avenue, Murray Hill, NJ;Bell Laboratories, Lucent Technologies Inc., 600 Mountain Avenue, Murray Hill, NJ;Bell Laboratories, Lucent Technologies Inc., 600 Mountain Avenue, Murray Hill, NJ

  • Venue:
  • SIGMOD '98 Proceedings of the 1998 ACM SIGMOD international conference on Management of data
  • Year:
  • 1998

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Abstract

Previous papers have postulated that traditional schemes for the management of replicated data are doomed to failure in practice due to a quartic (or worse) explosion in the probability of deadlocks. In this paper, we present results of a simulation study for three recently introduced protocols that guarantee global serializability and transaction atomicity without resorting to the two-phase commit protocol. The protocols analyzed in this paper include a global locking protocol [10], a “pessimistic” protocol based on a replication graph [5], and an “optimistic” protocol based on a replication graph [7]. The results of the study show a wide range of practical applicability for the lazy replica-update approach employed in these protocols. We show that under reasonable contention conditions and sufficiently high transaction rate, both replication-graph-based protocols outperform the global locking protocol. The distinctions among the protocols in terms of performance are significant. For example, an offered load where 70% - 80% of transactions under the global locking protocol were aborted, only 10% of transactions were aborted under the protocols based on the replication graph. The results of the study suggest that protocols based on a replication graph offer practical techniques for replica management. However, it also shows that performance deteriorates rapidly and dramatically when transaction throughput reaches a saturation point.