The processing of a join query in a distributed environment exacts the usage of both the network and its computational facilities. A formulation that accounts for both, and felicitously constructed as an integer linea...
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The processing of a join query in a distributed environment exacts the usage of both the network and its computational facilities. A formulation that accounts for both, and felicitously constructed as an integer linear program, is proposed. Information disseminated among the sites of a distributedsystem is to be amalgamated and presented to a user, in response to his request. From all possible strategies by which this might be achieved, one necessitating the smallest usage of system resources is to be chosen. The data transferal resources of the network are usually presumed to be of greatest significance, and therefore, an optimal strategy is most often defined to be one which minimizes the total transmission cost. One model conforming to this philosophy, appearing in [1), expediently takes the form of a linear integer program, and so forms the basis for further refinement. In the omission of processing costs, the various processor elements of the network are treated homologously;dissimilarities in processing ability are also ignored. By analyzing the nature of join computations at a single processor, the minimal transmission cost model can be hybridized to incorporate the cost of such computations and differences in processing power.
In distributed database systems, commit protocols are used to ensure the transaction atomicity. In the presence of failures, nonblocking commit protocols can guarantee the transaction atomicity without blocking the tr...
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In distributed database systems, commit protocols are used to ensure the transaction atomicity. In the presence of failures, nonblocking commit protocols can guarantee the transaction atomicity without blocking the transaction execution. A (resilient) decentralized nonblocking commit protocol (RDCP) is proper-ed for distributed database systems. This protocol is based on the hypercube network topology and is 'liub(log(2)(N)) - 2' resilient to node failures (N = number of system-nodes). The number of messages sent among the N nodes is 0(***(2)(2)(N)) which is only a factor of log(2)(N) over the message complexity lower bound 0(***(2)(N)) of decentralized commit protocols. Furthermore, RDCP is an optimistic nonblocking protocol. It aborts the transaction only when some nodes want to abort or some nodes fail before they make local decisions.
The benefit of using indexes for processing conjunctive queries in a databasesystem is well known. The use of indexes in distributed database systems is equally justified. In a distributeddatabase environment a rela...
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The benefit of using indexes for processing conjunctive queries in a databasesystem is well known. The use of indexes in distributed database systems is equally justified. In a distributeddatabase environment a relation may be horizontally partitioned across the nodes of the system and indexes may be created for the fragment of the relation that resides at each node. However, as an alternative, one might construct each index on the entire relation, i.e., global indexes, and then partition each index between the nodes. An approach is presented for processing such an index partitioning scheme in response to a conjunctive range query. The performance of these schemes is evaluated in terms of the response time of a query and the utilization of processors, disk, and communication network while varying the number of nodes and query mix.
The authors explain what is meant by a distributed database system and discuss its characteristics. They survey the state of distributeddatabase technology, focusing on how well products meet the goals of transparent...
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The authors explain what is meant by a distributed database system and discuss its characteristics. They survey the state of distributeddatabase technology, focusing on how well products meet the goals of transparent management of distributed and replicated data, reliability through distributed transactions, better performance, and easier, more economical system expansion. They then consider unsolved problems with regard to network scaling, distribution design, distributed query processing, distributed transaction processing, integration with distributed operating systems, and distributed multidatabasesystems
Catalog management schemes may affect the site autonomy, query optimization, view management and data distribution transparency. However, the performance comparison of various catalog architectures has received relati...
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Catalog management schemes may affect the site autonomy, query optimization, view management and data distribution transparency. However, the performance comparison of various catalog architectures has received relatively little attention. We employ the simulation models to investigate the relative performance of six catalog management schemes-a centralized catalog, two variations of fully replicated catalogs and three variations of partitioned catalogs-in a locally distributed database system and a geographically distributed database system. We show that three variations of partitioned catalogs perform better than the centralized catalogs and fully replicated catalogs over the wide range. The performance of centralized catalogs and fully replicated catalogs with quorum consensus are the worst because of the queuing delays in several queues. Our simulation results also indicate that the performance difference among the variations of partitioned catalogs is mainly due to the recompilation rate.
The study of communication designs in the context of the Raid system, a robust and adaptable distributed database system for transaction processing, is discussed. Related research work on local interprocess communicat...
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The study of communication designs in the context of the Raid system, a robust and adaptable distributed database system for transaction processing, is discussed. Related research work on local interprocess communication, remote interprocess communication, and communication protocols for both local area and wide area networks is briefly summarized. A series of experiments on the performance of the facilities available for building the Raid communication software is described. Raid's communication software, called Raidcomm, has evolved as a result of the knowledge gained both from other systems and from the authors' experiments. Several communication services and mechanisms that can be used to make Raid efficient are identified
The problem of failure recovery for a distributed database system is more complex than that for a centrally controlled databasesystem. If all the sites in a distributedsystem whose data are updated by a transaction...
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The problem of failure recovery for a distributed database system is more complex than that for a centrally controlled databasesystem. If all the sites in a distributedsystem whose data are updated by a transaction are not up and available at the time of transaction execution, either the updates must be cancelled for all sites or the updates for the temporarily inaccessible site must be saved for later delivery. A resilient control scheme for a distributed database system is described. The notion of a resilient system holds that a transaction cannot be executed if some true copies required by the transaction are not available within the partition where the transaction is executing. system objectives include the elimination of lost transaction updates, where the user receives an acknowledgment but updates are not posted, and lost transaction output, where updates are posted but the user receives no acknowledgment. Figures.
We present a methodology for structured database decomposition based on the relational data model. It is argued that in the distributeddatabase environment, structured database decomposition is attractive both for ef...
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We present a methodology for structured database decomposition based on the relational data model. It is argued that in the distributeddatabase environment, structured database decomposition is attractive both for efficiency and for database security considerations. Techniques for parallel processing and hashed access of structurally decomposed database are presented. Techniques for structured database decomposition to support multiple user views are also described. Structured database decomposition is most advantageous in a query only database environment with stable user views, although dynamic updates can also be handled using techniques described in this paper.
This paper presents a formal analysis of the concurrency control strategy of SDD-1. SDD-1, a system for distributeddatabases, is a prototype distributed database system being developed by Computer Corporation of Amer...
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The declining cost of computer hardware and the increasing data processing needs of geographically dispersed organizations have led to substantial interest in distributed data management. SDD-1 is a distributed databa...
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