The article introduces basics of classic distributeddatabase System (DDBS) and explains its unsuitability for dynamically changing networks such as Vehicular Ad-hoc Network (VANET). Thus a concept of a new architectu...
详细信息
The article introduces basics of classic distributeddatabase System (DDBS) and explains its unsuitability for dynamically changing networks such as Vehicular Ad-hoc Network (VANET). Thus a concept of a new architecture is proposed. This new architecture is designed for use in mobile networks as it solves problems of classic architecture, however as explained at the end of the article, it has some limitations of its own.
Task allocation models act as an important tool while designing a DDBS. distributed database systems are outcome of advancement in information and communication technologies. Importance of distributeddatabases and mo...
详细信息
ISBN:
(纸本)9781605606170
Task allocation models act as an important tool while designing a DDBS. distributed database systems are outcome of advancement in information and communication technologies. Importance of distributeddatabases and more specifically task based DDB designs in design development is gaining importance, which defines and makes it possible to identify the tasks handled as well as the distributed tasks on distributed system nodes. Any model describes a selected set of features or capabilities of the system and hide the other features. During this modeling process the main objective is to meet the specification and to complete the task in limited time with limited computing resources. Abstract cost models are best for algorithm designers when goal of system design is to design any algorithm, abstract cost models are best due to their common objectives of reflectivity, portability and simplicity.
The performance of distributed database systems can be adversely affected as a result of resource contention in the nodes and the communication links. The paper examines in detail the impact of resource contention on ...
详细信息
The performance of distributed database systems can be adversely affected as a result of resource contention in the nodes and the communication links. The paper examines in detail the impact of resource contention on the performance of fully replicated distributed database systems under different locking concurrency control protocols. The roles of communication overheads and transaction size on resource contention for the performance of Dynamic Two Phase Locking have been investigated and comparisons are made with results from two other locking concurrency control methods, namely the Immediate Restart (IR) and Limited Wailing (LW). The results suggested that Immediate Restart has the best performance under most conditions but it is more susceptible to changes in communication overheads and workload of undo operations.
distributed database systems are widely used to meet the demands of storing and managing computation-heavy workloads. To boost performance and minimize resource and data contention, these systems require selecting a d...
详细信息
distributed database systems are widely used to meet the demands of storing and managing computation-heavy workloads. To boost performance and minimize resource and data contention, these systems require selecting a distributed physical design that determines where to place data, and which data items to replicate and partition. Deciding on a physical design is difficult as each choice poses a trade-off in the design space, and a poor choice can significantly degrade performance. Current design decisions are typically static and cannot adapt to workload changes or are unable to combine multiple design choices such as data replication and data partitioning integrally. This paper presents MorphoSys, a distributeddatabase system that dynamically chooses, and alters, its physical design based on the workload. MorphoSys makes integrated design decisions for all of the data partitioning, replication and placement decisions on-the-fly using a learned cost model. MorphoSys provides efficient transaction execution in the face of design changes via a novel concurrency control and update propagation scheme. Our experimental evaluation, using several benchmark workloads and state-of-the-art comparison systems, shows that MorphoSys delivers excellent system performance through effective and efficient physical designs.
Global query management provides the ability to combine data from different local databases in a single retrieval operation. The necessity for global query management arises in an open, heterogeneous multidatabase sys...
详细信息
Global query management provides the ability to combine data from different local databases in a single retrieval operation. The necessity for global query management arises in an open, heterogeneous multidatabase system, since autonomy and heterogeneity of component databases have given rise to a number of new major issues regarding the global query optimization strategy and context mediation including data conversion and query translation. For instance, some local DBMSs never support semijoin operator which has been proposed in order that data transmission between sites could be reduced. In this regard, the global query optimization strategies developed for homogeneous distributed database systems make extensive use of semijoins which are not attractive in the multidatabase context since this may increase the local processing time. Moreover, these do not consider the cost incurred as a result of data conversion and query translation. Our basic principle to get a high performance is that we decompose a global query to the finest level of subqueries in order to explore all possible execution plans. This reduces the overall processing cost in an heterogeneous distributeddatabase system because subqueries that are sent to the local databases have to be converted. The lesser number of subqueries implies less conversion cost.
A queueing model is used to approximate static locking in distributed database systems without deadlocks. Then a random graph model to find the deadlock probability of each transaction is proposed. Finally, the above ...
详细信息
A queueing model is used to approximate static locking in distributed database systems without deadlocks. Then a random graph model to find the deadlock probability of each transaction is proposed. Finally, the above two models are integrated, so that given the transaction arrival rate, the response time and the effective throughput can be calculated.
The allocation of data to nodes in a computer communications network is a critical issue in distributeddatabase design, specially in wide area network where optimizing the distributed queries is the main objective. N...
详细信息
The allocation of data to nodes in a computer communications network is a critical issue in distributeddatabase design, specially in wide area network where optimizing the distributed queries is the main objective. Numerous models of data allocation have been presented so far (Ceri and Pelagatti, 1986;Lee et al., 1994;Apers, 1988;Mahmood et al., 1994;Theel, 1994;Saha and Mukherjee, 1994;Walfson and Jajodia, 1995), but no optimal or universally accepted algorithm exists yet, and very few algorithms have been implemented to date (Rob and Cornonel, 1993). In this paper a method to construct a model of data allocation for distributeddatabase system has been proposed. The adopted method for the construction of the data allocation model leads to an efficient model of its kind. The proposed model not only solves distributeddatabase design problem, but also solves distributeddatabase maintenance problem by covering initial allocation and post allocation of the data. The efficiency of proposed model has been proved by comparing proposed model with other relevant models.
作者：
RAM, SUNIV ARIZONA
KARL ELLER GRAD SCH MANAGEMENTDEPT MANAGEMENT INFORMAT SYSTTUCSONAZ 85721
In designing distributed database systems, an important issue is the location of various copies of each database, known as the File Allocation Problem (FAP). The impact of incorporating a specific concurrency control...
详细信息
In designing distributed database systems, an important issue is the location of various copies of each database, known as the File Allocation Problem (FAP). The impact of incorporating a specific concurrency control mechanism (CCM) into the FAP is examined. Several mechanisms can be used, and, depending on the choice, the communication flows in the network will vary. In order to allocate data optimally, the exact communication flows must be identified. This factor has been ignored in past research. The proposed nonlinear integer programming model, which uses the central node locking mechanism for concurrency control, provides a way to identify the communication flow. The model is solved using an algorithm called ZOOM/XMP, a computer code for solving zero-one mixed integer programming problems. The implementation shows that the allocation of a database at a particular node will depend on: 1. the ratio of queries to updates at the node, 2. the total traffic for that database arising at all other nodes, and 3. the capacity of the node.
Quantifying energy consumption of database operations is the foundation of building energy -efficient databasesystems. Existing approaches only focused on stand-alone database servers, while we are interested in mode...
详细信息
Quantifying energy consumption of database operations is the foundation of building energy -efficient databasesystems. Existing approaches only focused on stand-alone database servers, while we are interested in modeling energy consumption of database operations in the distributed environments. In this study, we aim at providing an accurate energy consumption model for queries executed in distributed database systems, profiling energy consumption characteristics of both the individual queries and the system as a whole, to guide the design of green databasesystems and to reveal opportunities for energy -efficient computing. As the execution of a distributed query is a combination of a set of subqueries that decomposed from it, we start from building energy models for individual subqueries by extracting basic operations that can effectively reflect their energy consumption. Then we use a bottom -up measuring and modeling method as the basis to provide a comprehensive energy estimation model for the entire distributed query. To validate the accuracy of the model, we use queries with a variety complexity that generated from three standard benchmarks (TPC-H, SSB, and Sysbench) on real distributeddatabases. Extensive experimental results show that our solution can achieve a high average accuracy of 94.63% for distributed queries. More importantly, based on these results we further explored energy consumption patterns for distributed queries and presented several important implications. And finally, a significant role of distributed joins has been discovered in saving both idle and dynamic energy cost of the system. We hope that taking advantage of our observations can help readers who wish to substantially improve energy efficiency for distributed database systems.
In a distributeddatabase system, an increase or shift in workload necessitates a reorganization of data amongst the servers, the system is conventionally shut down and an exhaustive data reorganization is performed. ...
详细信息
In a distributeddatabase system, an increase or shift in workload necessitates a reorganization of data amongst the servers, the system is conventionally shut down and an exhaustive data reorganization is performed. This static methodology results in low data availability and in high costs for exhaustive data reorganizations. We present the Algorithm MIGRATE heuristic for dynamic data migration. Algorithms in previous research perform reorganization in a static fashion, meaning that data is unavailable during the data reorganization process. Research specifically addressing dynamic file migration concentrates on if and when to migrate data rather than on how to migrate the data.
暂无评论