Showing papers on "Weak consistency published in 1990"
TL;DR: In this article, it was shown that the weak consistency property does not hold for large classes of decision procedures, and the geometric reasons why such a property fails to hold are described, and a general theorem is given to characterize the procedures that satisfy this property.
Abstract: If a statistical or a voting decision procedure is used by several subpopulations and if each reaches an identical conclusion, then one might expect this conclusion to be the outcome for the full group. It is shown that this property fails to hold for large classes of decision procedures. The geometric reasons why the consistency does not hold are described. A general theorem is given to characterize the procedures that satisfy this property of “weak consistency”.
51 citations
08 Nov 1990
TL;DR: The Open System for Consistency and Replication (OSCAR), an architecture for a weak-consistency replication system, is presented and a novel technique called mediation ensures reliable propagation of the updates throughout the system.
Abstract: The proliferation of internetworks and distributed applications has increased the demand for geographically distributed replicated databases The traditional approach of strong consistency is difficult to achieve across an internetwork In contrast to strong consistency, a database replication system that provides weak consistency permits greater availability by allowing temporary inconsistencies to develop among the replicas The Open System for Consistency and Replication (OSCAR), an architecture for a weak-consistency replication system, is presented The approach to reliable replication is to use two complementary mechanisms When an update initially enters the replication system, it is unreliably pushed to all other replicas A novel technique called mediation ensures reliable propagation of the updates throughout the system OSCAR provides appropriate weak consistency for a variety of applications by simultaneously supporting several weak-consistency methods Its modular design permits its components to be configured for different networks and allows its algorithms to be selected and tuned for different environments and applications >
29 citations
24 Sep 1990
TL;DR: This paper presents a forwarding strategy for missing updates and a method to globally order conflicting transactions in a partitioned system to define a new concept for control as opposed to the traditional adaptation/recovery paradigm for replica control.
Abstract: In distributed systems replication is used to enhance availability and performance Concurrent access to copies on different sites must be synchronized so transactions remain serializable The main difficulty is the possibility of a partition of the network due to site or communication failures Several protocols have been designed to synchronize transactions running in different components Most pessimistic algorithms restrict access to a unique component per object and impose mutual consistency of copies In this paper we show that this is not necessary for pessimistic control We present a forwarding strategy for missing updates and a method to globally order conflicting transactions in a partitioned system This enables consistent views of objects in minority components, logical conflicts in different components and one-copy serializability We present an algorithm based on these ideas which achieves higher availability than other pessimistic protocols This leads us to define a new concept for control as opposed to the traditional adaptation/recovery paradigm for replica control
1 citations