José Ramón Juárez-Rodríguez

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Several previous works have proven that there is no way of guaranteeing a snapshot isolation level in symmetrical replicated database systems without blocking transactions when they are started. As a result of this, the generalized snapshot isolation (GSI) level was defined, relaxing a bit the freshness of the snapshot being taken when a transaction is(More)
We describe a recovery protocol which boosts availability, fault tolerance and performance by enabling failed network nodes to resume an active role immediately after they start recovering. The protocol is designed to work in tandem with middleware-based eager update-everywhere strategies and related group communication systems. The latter provide view(More)
Middleware database replication is a way to increase availability and afford site failures for dynamic content Websites. There are several replication protocols that ensure data consistency for these systems. The most attractive ones are those providing generalized snapshot isolation (GSI), as read operations never block. These replication protocols are(More)
Database replication is a way to increase system performance and fault-tolerance of a given system. The price to pay is the effort needed to guarantee data consistency, and this is not an easy task. In this paper, we introduce a description of two 1-Copy-Serializable (1CS) [1] eager update everywhere replication protocols. The preliminary results of their(More)
Where Multicast Writesets Never Get Aborted J.R. Juárez-Rodrı́guez, J.E. Armendáriz-Iñigo, F.D. Muñoz-Escoı́ , J.R. González de Mendı́vil , J.R. Garitagoitia 1 1 Dpto. Ingenierı́a Matemática e Informática 2 Instituto Tecnológico de Informática Universidad Pública de Navarra Universidad Politécnica de Valencia Campus de Arrosadı́a s/n Camino de Vera s/n(More)
Middleware data replication techniques are a way to increase performance and fault tolerance without modifying the internals of a DBMS. However, they introduce overheads that may lead to poor response times. In this paper a modification of the O2PL protocol is introduced. It orders conflicting transactions by using their priority, instead of the total order(More)
Replication increases the availability of data. Availability, consistency and integrity are competing objectives. They need to be reconciled, and adapted to the needs of different applications and users, by appropriate replication strategies. We outline work in progress on a middleware architecture for replicated databases. It simultaneously maintains(More)
In database replication, primary-copy systems sort out easily the problem of keeping replicate data consistent by allowing only updates at the primary copy. While this kind of systems are very efficient with workloads dominated by read-only transactions, the update-everywhere approach is more suitable for heavy update loads. However, it behaves worse when(More)