In this paper, we address the performance of distributed database systems with buffer constraints. Specifically, our objective is to design and analyze efficient data allocation and replication strategies to minimize ...
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In this paper, we address the performance of distributed database systems with buffer constraints. Specifically, our objective is to design and analyze efficient data allocation and replication strategies to minimize the total servicing cost for an arbitrary read/write request sequence, under finite buffer constraints of the nodes in the system. When the available buffer space in a node is not enough to store a copy of an object, the decision has to be made on whether or not we should evict one or more objects in use to give room for the new object copy. In this paper, we design and analyze the data replication strategies with the model of Dynamic Window Mechanism (DWM) algorithm jointly implemented with different types of object replacement strategies ( No Replacement, LRU, and LFU) commonly found in practice. We consider situations wherein the object sizes are identical as well as heterogeneous. We will show the impact on the performance of the allocation and replication strategies due to the limited local database buffer capacities. We analyze and quantify theoretically ( using competitive analysis) the performances of all the proposed algorithms. Further, we perform rigorous simulation experiments to validate the findings with respect to several influencing parameters. Several useful conclusions are drawn based on the experimental results and we highlight the usefulness of the algorithms under different situations.
The assembly flowshop scheduling problem has been addressed recently in the literature, There are many problems that can be modeled as assembly flowshop scheduling problems including queries scheduling on distributed ...
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The assembly flowshop scheduling problem has been addressed recently in the literature, There are many problems that can be modeled as assembly flowshop scheduling problems including queries scheduling on distributed database systems and computer manufacturing. The problem has been addressed with respect to either makespan or total completion time criterion in the literature. In this paper, we address the problem with respect to a due date-based performance measure, i.e., maximum lateness. We formulate the problem and obtain a dominance relation. Moreover, we propose three heuristics for the problem: particle swarm optimization (PSO), Tabu search. and EDD. PSO has been used in the areas of function optimization, artificial neural network training, and fuzzy system control in the literature. In this paper, we show how it can be used for scheduling problems. We have conducted extensive computational experiments to compare the three heuristics along with a random solution. The computational analysis indicates that Tabu outperforms the others for the case when the due dates range is relatively wide. It also indicates that the PSO significantly outperforms the others for difficult problems. i.e., tight due dates. Moreover, for difficult problems, the developed dominance relation helps reduce error by 65%. (c) 2004 Elsevier Ltd. All rights reserved.
After an attack on a databasesystem, evaluation of damage must be performed as soon the attack is identified. Otherwise, the initial damage will spread to other parts of the database via valid transactions, consequen...
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ISBN:
(纸本)9781424401291
After an attack on a databasesystem, evaluation of damage must be performed as soon the attack is identified. Otherwise, the initial damage will spread to other parts of the database via valid transactions, consequently resulting in denial-of-service. Damage assessment in a distributed database system is a complicated task due to intricate transaction relationships among distributed sites. In these systems, when any sub-transaction reads a damaged data at any site, the entire transaction of which the sub-transaction is a part, is considered affected by the damage. Hence, the data items updated by that transaction irrespective of sites are also considered damaged. This research focuses on damage assessment procedure for distributed database systems and uses a two-pass algorithm to obtain the final fist of affected data items. The advantages of this method are: (1) the process is fully distributed in the sense that every site will execute the same algorithm, (2) the amount of data to be exchanged between the sites is minimized to the list of affected items at each site instead of the entire log, and (3) the local damage assessors can be executed in parallel at their respective sites.
We suggest a new probe message structure and an efficient probe-based deadlock detection and recovery algorithm that can be used in distributed database systems. We determine the characteristics of the probe messages ...
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We suggest a new probe message structure and an efficient probe-based deadlock detection and recovery algorithm that can be used in distributed database systems. We determine the characteristics of the probe messages and suggest an algorithm that can reduce the communication cost required for deadlock detection and recovery.
In this paper, we consider optimal mirror allocation problems for the purpose of load balancing in network servers. We focus on constructing high-reliability networks and propose the optimal mirror allocation model su...
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In this paper, we consider optimal mirror allocation problems for the purpose of load balancing in network servers. We focus on constructing high-reliability networks and propose the optimal mirror allocation model such that the system reliability is maximized subject to costs and delays, in view of the trade-off between the reliability and cost. This optimization model is capable of dealing with various kinds of network topologies, although for simplicity, we assume the read-only situation. We formulate this optimization problem into a 0 1 integer programming model, and we use an approximate method for numerical analysis in order to analyze more large-scale systems. Our objective is to find the optimal mirror allocation by solving this model, and to show quantitatively the general characteristics of the load balancing and the improvement of the system reliability by the distributed mirror allocation.
Due to the recent expansion of network bandwidth, the data propagation delay has become a significant factor which influences the system performance in place of the data transmission delay. Based on this fact, we have...
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ISBN:
(纸本)0909925836
Due to the recent expansion of network bandwidth, the data propagation delay has become a significant factor which influences the system performance in place of the data transmission delay. Based on this fact, we have proposed a new technology to reduce the bad influence of propagation delay on the performance of distributed database system by relocating dynamically the database through networks, which we call database migration. Furthermore, we have proposed a database relocation method to choose the transaction processing method between the conventional database fixed method and the proposed database migration method by giving consideration to the transaction complexity. In this paper, we explain our distributed database system with database migration mechanism based on these proposals, and the implementation of the DB-MANα system as a prototype system. The DB-MANα system reduces the database migration time by using a main memory database technique, which induces us to add a backup management mechanism for migratory databases. Moreover, we show some measurement results for the performance evaluation of the DB-MANα system. The results show that the implemented system works well in a practical environment.
In distributed network systems, it is one of the most important problems how to assign the files to servers in view of cost and delay. It is obvious that there is a trading-off relationship between costs and delays in...
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In distributed network systems, it is one of the most important problems how to assign the files to servers in view of cost and delay. It is obvious that there is a trading-off relationship between costs and delays in these systems. In order to evaluate the optimization that the total cost is minimized subject to the total delay, we have presented the Optimal File Allocation Model as 0-1 integer programming, and have investigated the general characteristics in distributedsystems. In this model, we have introduced many cost and delay parameters to evaluate the total cost and delay in the system more exactly. In constructing practical systems, it is necessary to investigate the weight and the contribution of each parameter to the total cost. It is very useful to show how to estimate cost and delay parameters on the basis of this analysis. In this paper, we analyze the sensitivity of these parameters and make clear the influence between principal parameters.
A mobile transaction management system enables users to receive transaction based services from both static and mobile hosts distributed in a large scale of network. The difficulty lies in the heterogeneity of compute...
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ISBN:
(纸本)0818690968
A mobile transaction management system enables users to receive transaction based services from both static and mobile hosts distributed in a large scale of network. The difficulty lies in the heterogeneity of computer systems and in the communication control to guarantee concurrency and consistency of transaction operations. The World Wide Web offers a uniformed vehicle to interface with users ubiquitously and an ideal architecture to implement mobile transaction systems. This paper reports a design using Java, JDBC and Web browser to implement a distributed database system, particularly a transaction management system covers mobile hosts and static workstations/PCs in which data and sewers are replicated.
This thesis described the integration of the real-time motion control network with switch high-speed Ethernet technology and distributeddatabase technology. An application is introduced at the end.
ISBN:
(纸本)7312012035
This thesis described the integration of the real-time motion control network with switch high-speed Ethernet technology and distributeddatabase technology. An application is introduced at the end.
The problem of describing minimal response time execution strategies in evaluating the join of several fragmented database relations, is considered. The consequential optimization problem assumes the convenient form o...
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The problem of describing minimal response time execution strategies in evaluating the join of several fragmented database relations, is considered. The consequential optimization problem assumes the convenient form of a min-max integer program. With further attention, various generalizations are realized that also include the performance objective of total execution cost. Tables of data logically conforming to the relational model of information are, at the physical level, frequently divided into numerous pieces. These fragments are found disseminated amongst the various sites of a distributed database system, with each one possibly replicated at any number of separate facilities. A submission demanding the amalgamation of many such relations is resolved by joining together their sets of component fragments in an appropriate manner, as defined by complicated patterns of overlapping attribute values. The final result is realized by then concatenating the products of these computations. This process is to be performed under the supervision of the database management system in such a way as to minimize the time taken, as perceived by the user who issued the request. These developments are based upon earlier investigations [1-5] that consider only the alternative optimization goal of minimal execution cost. With this in mind, several different different approaches may be taken to realize distinct hybrid models that give due regard to both measures of join query performance.
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