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Validation concurrency control protocol in parallel real-time database systems 被引量:3
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作者 LEI Xiang-dong(雷向东) YUAN Xiao-li(袁晓莉) 《Journal of Central South University of Technology》 2002年第3期197-201,共5页
In parallel real-time database systems, concurrency control protocols must satisfy time constraints as well as the integrity constraints. The authors present a validation concurrency control(VCC) protocol, which can e... In parallel real-time database systems, concurrency control protocols must satisfy time constraints as well as the integrity constraints. The authors present a validation concurrency control(VCC) protocol, which can enhance the performance of real-time concurrency control mechanism by reducing the number of transactions that might miss their deadlines, and compare the performance of validation concurrency control protocol with that of HP2PL(High priority two phase locking) protocol and OCC-TI-WAIT-50(Optimistic concurrency control-time interval-wait-50) protocol under shared-disk architecture by simulation. The simulation results reveal that the protocol the author presented can effectively reduce the number of transactions restarting which might miss their deadlines and performs better than HP2PL and OCC-TI-WAIT-50. It works well when arrival rate of transaction is lesser than threshold. However, due to resource contention the percentage of missing deadline increases sharply when arrival rate is greater than the threshold. 展开更多
关键词 parallel database system real-time database CONCURRENCY control VALIDATION TRANSACTIONS
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Scheduling transactions in mobile distributed real-time database systems 被引量:1
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作者 雷向东 赵跃龙 +1 位作者 陈松乔 袁晓莉 《Journal of Central South University of Technology》 EI 2008年第4期545-551,共7页
A DMVOCC-MVDA (distributed multiversion optimistic concurrency control with multiversion dynamic adjustment) protocol was presented to process mobile distributed real-time transaction in mobile broadcast environment... A DMVOCC-MVDA (distributed multiversion optimistic concurrency control with multiversion dynamic adjustment) protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load (think time is ls) the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols. 展开更多
关键词 mobile distributed real-time database systems muliversion optimistic concurrency control multiversion dynamic adjustment pre-validation multiversion data broadcast
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New multi-DSP parallel computing architecture for real-time image processing 被引量:4
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作者 Hu Junhong Zhang Tianxu Jiang Haoyang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2006年第4期883-889,共7页
The flexibility of traditional image processing system is limited because those system are designed for specific applications. In this paper, a new TMS320C64x-based multi-DSP parallel computing architecture is present... The flexibility of traditional image processing system is limited because those system are designed for specific applications. In this paper, a new TMS320C64x-based multi-DSP parallel computing architecture is presented. It has many promising characteristics such as powerful computing capability, broad I/O bandwidth, topology flexibility, and expansibility. The parallel system performance is evaluated by practical experiment. 展开更多
关键词 parallel computing image processing real-time computer architecture
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A Class of Parallel Algorithms of Real-TimeNumerical Simulation for Stiff Dynamic System 被引量:2
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作者 Cao Xuenian Liu Degui Li Shoufu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2000年第4期51-58,共8页
In this paper a class of real-time parallel modified Rosenbrock methods of numerical simulation is constructed for stiff dynamic systems on a multiprocessor system, and convergence and numerical stability of these met... In this paper a class of real-time parallel modified Rosenbrock methods of numerical simulation is constructed for stiff dynamic systems on a multiprocessor system, and convergence and numerical stability of these methods are discussed. A-stable real-time parallel formula of two-stage third-order and A(α)-stable real-time parallel formula with o ≈ 89.96° of three-stage fourth-order are particularly given. The numerical simulation experiments in parallel environment show that the class of algorithms is efficient and applicable, with greater speedup. 展开更多
关键词 Dynamic system real-time simulation parallel algorithms?
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A Class of Real-Time Parallel Combined Methods ofDigital Simulation for Large Systems
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作者 Liu Degui & Chen Lirong(Beijing Institute of Computer Application and Simulation Technology, 100854, P. R. China) 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2000年第2期25-31,共7页
In this paper, a class of real-time parallel combined methods (RTPCM) of the digital simulation for a partitioned large system is presented. By means of combination of the parallelism across the system with the parall... In this paper, a class of real-time parallel combined methods (RTPCM) of the digital simulation for a partitioned large system is presented. By means of combination of the parallelism across the system with the parallelism across the method, stiff and non-stiff subsystems are solved in parallel on parallel computer by a parallel Rosenbrock method and a parallel RK method, respectively. Their construction, convergence and numerical stability are discussed, and the digitalsimulation experiments are conducted. 展开更多
关键词 Large system real-time parallel combined method parallel computer
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Class of modified parallel combined methods of real-time numerical simulation for a stiff system
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作者 朱珍民 刘德贵 陈丽容 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2004年第3期387-391,共5页
A class of modified parallel combined methods of real-time numerical simulation are presented for a stiff dynamic system. By combining the parallelism across the system with the parallelism across the method, and rela... A class of modified parallel combined methods of real-time numerical simulation are presented for a stiff dynamic system. By combining the parallelism across the system with the parallelism across the method, and relaxing the dependence of stage value computation on sampling time of input function, a class of modified real-time parallel combined methods are constructed. Stiff and nonstiff subsystems are solved in parallel on a parallel computer by a parallel Rosen-brock method and a parallel RK method, respectively. Their order conditions and convergences are discussed. The numerical simulation experiments show that this class of modified algorithms can get high speed and efficiency. 展开更多
关键词 stiff system real-time numerical simulation parallel combined method.
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A sensor transaction scheduling algorithm for maintaining real-time data temporal validity 被引量:1
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作者 白天 李国徽 刘云生 《Journal of Central South University》 SCIE EI CAS 2011年第6期2068-2073,共6页
A new scheduling algorithm called deferrable scheduling with time slice exchange (DS-EXC) was proposed to maintain the temporal validity of real-time data. In DS-EXC, the time slice exchange method was designed to fur... A new scheduling algorithm called deferrable scheduling with time slice exchange (DS-EXC) was proposed to maintain the temporal validity of real-time data. In DS-EXC, the time slice exchange method was designed to further defer the release time of transaction instances derived by the deferrable scheduling algorithm (DS-FP). In this way, more CPU time would be left for lower priority transactions and other transactions. In order to minimize the scheduling overhead, an off-line scheme was designed. In particular, the schedule for a transaction set is generated off-line until a repeating pattern is found, and then the pattern is used to construct the schedule on-line. The performance of DS-EXC was evaluated by sets of experiments. The results show that DS-EXC outperforms DS-FP in terms of increasing schedulable ratio. It also provides better performance under mixed workloads. 展开更多
关键词 temporal validity real-time database sensor transaction
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High performance reconfigurable hardware system for real-time image processing
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作者 赵广州 张天序 +2 位作者 王岳环 曹治国 左峥嵘 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第3期502-509,共8页
A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-B... A novel reconfigurable hardware system which uses both muhi-DSP and FPGA to attain high performance and real-time image processing are presented. The system structure and working principle of mainly processing multi-BSP board, extended multi-DSP board are analysed. The outstanding advantage is that the communication among different board components of this system is supported by high speed link ports & serial ports for increasing the system performance and computational power. Then the implementation of embedded real-time operating systems (RTOS) by us is discussed in detail. In this system, we adopt two kinds of parallel structures controlled by RTOS for parallel processing of algorithms. The experimental results show that exploitive period of the system is short, and maintenance convenient. Thus it is suitable for real-time image processing and can get satisfactory effect of image recognition. 展开更多
关键词 MULTI-DSP fidd programmable gate arrays real-time image processing real time operating systems parallel structure.
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论司法公共表达与“网库并行”案例发布模式的建构 被引量:1
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作者 张杰 《交大法学》 北大核心 2025年第1期68-85,共18页
司法公共表达是司法公开内容质效的提升,也与法律沟通存在区别。案例是司法公共表达的重要载体。一国案例发布模式应当根据法域特征、法治传统以及民众心理等综合选择,并契合司法公共表达效果予以优化。我国应当采取上级司法机关审核后... 司法公共表达是司法公开内容质效的提升,也与法律沟通存在区别。案例是司法公共表达的重要载体。一国案例发布模式应当根据法域特征、法治传统以及民众心理等综合选择,并契合司法公共表达效果予以优化。我国应当采取上级司法机关审核后选择性公开的方式发布案例。当前我国形成了“中国裁判文书网”发布文书案例和“人民法院案例库”收录典型案例的“网库并行”案例发布模式。以司法公共表达为视域,应当建构案例审核筛选、信息过滤、炒作规避、数据安全等机制,未来还应加强案例发布的立法保障和技术安全,强化案例发布形式内容的优化,在更高层面统筹建设“司法案例库”,实现更大范围公开案例,推进案例发布在司法公共表达中发挥更大作用。 展开更多
关键词 司法公共表达 司法案例 “网库并行” 人民法院案例库 中国裁判文书网
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Forward kinematics analysis of parallel manipulator using modified global Newton-Raphson method 被引量:22
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作者 杨炽夫 郑淑涛 +2 位作者 靳军 朱思斌 韩俊伟 《Journal of Central South University》 SCIE EI CAS 2010年第6期1264-1270,共7页
In order to obtain direct solutions of parallel manipulator without divergence in real time,a modified global Newton-Raphson(MGNR) algorithm was proposed for forward kinematics analysis of six-degree-of-freedom(DOF) p... In order to obtain direct solutions of parallel manipulator without divergence in real time,a modified global Newton-Raphson(MGNR) algorithm was proposed for forward kinematics analysis of six-degree-of-freedom(DOF) parallel manipulator.Based on geometrical frame of parallel manipulator,the highly nonlinear equations of kinematics were derived using analytical approach.The MGNR algorithm was developed for the nonlinear equations based on Tailor expansion and Newton-Raphson iteration.The procedure of MGNR algorithm was programmed in Matlab/Simulink and compiled to a real-time computer with Microsoft visual studio.NET for implementation.The performance of the MGNR algorithms for 6-DOF parallel manipulator was analyzed and confirmed.Applying the MGNR algorithm,the real generalized pose of moving platform is solved by using the set of given positions of actuators.The theoretical analysis and numerical results indicate that the presented method can achieve the numerical convergent solution in less than 1 ms with high accuracy(1×10-9 m in linear motion and 1×10-9 rad in angular motion),even the initial guess value is far from the root. 展开更多
关键词 parallel manipulator forward kinematics global Newton-Raphson real-time system
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Parallelism of spatial data mining based on autocorrelation decision tree 被引量:1
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作者 Zhang Shuyu Zhu Zhongying 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第4期947-956,共10页
Define and theory of autocorrelation decision tree (ADT) is introduced. In spatial data mining, spatial parallel query are very expensive operations. A new parallel algorithm in terms of autocorrelation decision tre... Define and theory of autocorrelation decision tree (ADT) is introduced. In spatial data mining, spatial parallel query are very expensive operations. A new parallel algorithm in terms of autocorrelation decision tree is presented. And the new method reduces CPU- and I/O-time and improves the query efficiency of spatial data. For dynamic load balancing, there are better control and optimization. Experimental performance comparison shows that the improved algorithm can obtain a optimal accelerator with the same quantities of processors. There are more completely accesses on nodes. And an individual implement of intelligent information retrieval for spatial data mining is presented. 展开更多
关键词 spatial databases autocorrelation attribute decision tree parallelism.
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面向分布式数据库的算子并行优化策略 被引量:2
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作者 刘文洁 吕靖超 《西北工业大学学报》 EI CAS CSCD 北大核心 2024年第3期453-459,共7页
随着网络技术的不断发展,数据规模呈现爆发式增长,使得传统的单机数据库逐步被分布式数据库所取代。分布式数据库采用节点协同工作方式解决了大规模数据存储问题,但由于增加了节点间通信开销,查询效率却不如单机数据库。分布式架构下,... 随着网络技术的不断发展,数据规模呈现爆发式增长,使得传统的单机数据库逐步被分布式数据库所取代。分布式数据库采用节点协同工作方式解决了大规模数据存储问题,但由于增加了节点间通信开销,查询效率却不如单机数据库。分布式架构下,存储节点的数据仅用作多备份的冗余,为系统故障时提供数据恢复,并未被利用起来改善查询效率。针对上述问题,提出了一种面向分布式数据库的算子并行优化策略,通过对关键物理算子进行拆分,将拆分后的子请求均匀分配到存储层多个节点,由多个节点并行处理,从而减少查询响应时间。上述策略已经在分布式数据库CBase上进行了应用,实验表明,提出的并行优化策略可显著缩短SQL请求查询时间,并提高系统资源利用率。 展开更多
关键词 分布式数据库 并行查询 查询优化 负载均衡 数据分区
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架构大数据:挑战、现状与展望 被引量:620
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作者 王珊 王会举 +1 位作者 覃雄派 周烜 《计算机学报》 EI CSCD 北大核心 2011年第10期1741-1752,共12页
大数据分析相比于传统的数据仓库应用,具有数据量大、查询分析复杂等特点.为了设计适合大数据分析的数据仓库架构,文中列举了大数据分析平台需要具备的几个重要特性,对当前的主流实现平台——并行数据库、MapReduce及基于两者的混合架... 大数据分析相比于传统的数据仓库应用,具有数据量大、查询分析复杂等特点.为了设计适合大数据分析的数据仓库架构,文中列举了大数据分析平台需要具备的几个重要特性,对当前的主流实现平台——并行数据库、MapReduce及基于两者的混合架构进行了分析归纳,指出了各自的优势及不足,同时也对各个方向的研究现状及作者在大数据分析方面的努力进行了介绍,对未来研究做了展望. 展开更多
关键词 大数据 大规模可扩展 MAPREDUCE 并行数据库 深度分析
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大数据管理技术研究综述 被引量:14
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作者 张滨 陈吉荣 乐嘉锦 《计算机应用与软件》 CSCD 北大核心 2014年第11期1-5,10,共6页
大数据具有规模大、深度大、宽度大、处理时间短、硬件系统普通化、软件系统开源化等特点。传统关系型数据库在对大数据进行操作时,系统性能严重下降。因此,大数据管理技术研究成为当前研究热点。分别从并行数据库,面向大数据处理的MapR... 大数据具有规模大、深度大、宽度大、处理时间短、硬件系统普通化、软件系统开源化等特点。传统关系型数据库在对大数据进行操作时,系统性能严重下降。因此,大数据管理技术研究成为当前研究热点。分别从并行数据库,面向大数据处理的MapReduce模型,NoSQL与数据库技术的对比以及MapReduce与数据库技术相结合四个方面,对国内外的研究发展状况进行分析和评述,最后展望了未来大数据研究发展方向。 展开更多
关键词 大数据 数据库 MAPREDUCE 并行数据库系统 非关系型数据库
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并行数据库的改进Hash划分方法及并行Join算法 被引量:4
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作者 陆丽娜 孟虹 +1 位作者 魏恒义 杨麦顺 《计算机研究与发展》 EI CSCD 北大核心 2000年第2期159-163,共5页
文中提出了Hash 划分的改进方法——IH 划分. IH划分为结点扩充时数据的重新划分提供了方便.在论述IH 划分的基础上,给出了基于该数据划分方法的并行Join 算法.利用已有的数据分布,文中提出的并行Join 算法提高... 文中提出了Hash 划分的改进方法——IH 划分. IH划分为结点扩充时数据的重新划分提供了方便.在论述IH 划分的基础上,给出了基于该数据划分方法的并行Join 算法.利用已有的数据分布,文中提出的并行Join 算法提高了算法的效率.最后,从理论上对以上并行算法的计算复杂性进行了分析. 展开更多
关键词 数据 并行数据库 数据划分 JOIN算法
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基于密度的并行聚类算法 被引量:9
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作者 陈敏 高学东 +1 位作者 栾绍峻 郗玉平 《计算机工程》 CAS CSCD 北大核心 2010年第11期8-10,共3页
为满足大规模空间数据库的聚类需求,面向计算机集群,提出一种基于密度的并行聚类算法。该算法根据数据库分布特征进行数据分区,在每一个节点上对数据块并行聚类,在主节点上合并聚类结果。实验结果表明,该算法的计算速度随着节点数的增... 为满足大规模空间数据库的聚类需求,面向计算机集群,提出一种基于密度的并行聚类算法。该算法根据数据库分布特征进行数据分区,在每一个节点上对数据块并行聚类,在主节点上合并聚类结果。实验结果表明,该算法的计算速度随着节点数的增多呈线性增加,具有较好的延展性。 展开更多
关键词 并行聚类 计算机集群 数据库 延展性
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一种并行XML数据库分片策略 被引量:7
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作者 王国仁 汤南 +2 位作者 于亚新 孙冰 于戈 《软件学报》 EI CSCD 北大核心 2006年第4期770-781,共12页
主要研究XML文档的并行数据分片策略,以便能够并行处理XML查询.为了描述XML数据分片,提出了媒介节点的概念.一组媒介节点的集合可以将一棵XML数据树分割成一棵根树和一组子树的集合:根树将在所有站点中复制;而子树集合则可以根据用户查... 主要研究XML文档的并行数据分片策略,以便能够并行处理XML查询.为了描述XML数据分片,提出了媒介节点的概念.一组媒介节点的集合可以将一棵XML数据树分割成一棵根树和一组子树的集合:根树将在所有站点中复制;而子树集合则可以根据用户查询的工作负载被均匀地分片到各个站点中.对于同一棵XML数据树,会有很多种媒介节点的集合;而不同的媒介节点集合会产生不同的数据分片结果.然后,依据各个数据分片中的用户查询工作量是否均衡,来衡量一个分片的好坏.选择一组最佳的媒介节点集合是一个NP-hard问题.为了解决此问题,设计了一组启发式优化规则.基于这一思想,提出并实现了一种基于媒介节点的XML数据分片算法WIN(workload-awareintermediarynodesdataplacementstrategy).大量实验结果证明:WIN算法的性能要优于以往的并行XML数据分片策略. 展开更多
关键词 并行数据库 XML文档 工作负载 数据分片 媒介节点
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基于固态硬盘内部并行的数据库表扫描与聚集 被引量:10
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作者 范玉雷 赖文豫 孟小峰 《计算机学报》 EI CSCD 北大核心 2012年第11期2327-2336,共10页
随着基于闪存的固态硬盘在个人计算机和企业服务器上的广泛应用,固态硬盘受到学术界和工业界越来越多的关注.除了具有闪存存储器的优良特性之外,固态硬盘内部还具有丰富的并行特性.传统数据库系统的物理操作表扫描和上层聚集操作是针对... 随着基于闪存的固态硬盘在个人计算机和企业服务器上的广泛应用,固态硬盘受到学术界和工业界越来越多的关注.除了具有闪存存储器的优良特性之外,固态硬盘内部还具有丰富的并行特性.传统数据库系统的物理操作表扫描和上层聚集操作是针对磁盘的机械特性和对称读写特性而设计的,并不能发挥固态硬盘内部并行特性的优势.文中首先将固态硬盘作为一个黑盒进行探测以了解其内部的并行特性.在此基础上,对传统数据库表扫描操作进行相应的改进,提出一种并行表扫描模型ParaSSDScan以充分利用固态硬盘内部丰富的并行特性.其次,基于并行表扫描模型,文中还提出一种高效的并行聚集操作模型ParaSSDAggr,并利用该聚集操作模型实现几种常见聚集操作.最后,通过实验表明并行表扫描和并行聚集操作的性能较之传统数据库表扫描和聚集操作的性能分别提高了3倍和4倍,同时实验结果还表明并行聚集操作对内存的需求不大.并行表扫描和并行聚集操作大大提高了表扫描和聚集操作的性能,充分说明了固态硬盘内部并行特性的优越性. 展开更多
关键词 固态硬盘 闪存数据库 并行表扫描 并行聚集
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面向批量插入优化的并行存储引擎MTPower 被引量:5
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作者 陈虎 唐海浩 +1 位作者 廖江苗 彭江峰 《计算机学报》 EI CSCD 北大核心 2010年第8期1492-1499,共8页
针对多核处理器的特点,文章提出了一个符合MySQL接口标准的并行存储引擎MTPower.该存储引擎着重利用多核处理器的并行计算能力提升批量插入过程中的索引产生过程,主要包含存储引擎接口、并行批量线性Hash索引、并行批量B+树插入、支持... 针对多核处理器的特点,文章提出了一个符合MySQL接口标准的并行存储引擎MTPower.该存储引擎着重利用多核处理器的并行计算能力提升批量插入过程中的索引产生过程,主要包含存储引擎接口、并行批量线性Hash索引、并行批量B+树插入、支持并行访问的磁盘存储缓冲等部分.测试结果表明,在批量插入记录且需要创建Hash和B+树索引时,MTPower的性能比经典的单线程存储引擎MyISAM最高可以提高6.1倍和4.8倍;在系统中线程总数略大于处理器核数时,MTPower可以达到最佳性能;在处理器核的数量增加时,MTPower的性能也能随之提高. 展开更多
关键词 并行数据库 Hash并行索引 B+树并行索引 磁盘缓冲 多核处理器
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基于MapReduce的关系型数据仓库并行查询 被引量:9
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作者 师金钢 鲍玉斌 +1 位作者 冷芳玲 于戈 《东北大学学报(自然科学版)》 EI CAS CSCD 北大核心 2011年第5期626-629,共4页
针对MapReduce框架与传统关系型数据库兼容性不好的问题,提出了一种基于分块结构的分布式关系数据库ChunkDB.并对MapReduce架构进行了扩展设计,使ChunkDB与MapReduce有效结合,将MapReduce的扩展性、易操作性、高并行性与关系数据库的索... 针对MapReduce框架与传统关系型数据库兼容性不好的问题,提出了一种基于分块结构的分布式关系数据库ChunkDB.并对MapReduce架构进行了扩展设计,使ChunkDB与MapReduce有效结合,将MapReduce的扩展性、易操作性、高并行性与关系数据库的索引等查询优化优势相结合.实验证明基于MapReduce的ChunkDB数据库能够为数据仓库应用提供快速高效的并行查询. 展开更多
关键词 MAPREDUCE 数据仓库 并行计算 分布式数据库 查询优化
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