A Surfing Concurrence Transaction Model for Key-Value NoSQL Databases

As more and more application systems related to big data were developed, NoSQL (Not Only SQL) database systems are becoming more and more popular. In order to add transaction features for some NoSQL database systems, many scholars have tried different techniques. Unfortunately, there is a lack of research on Redis’s transaction in the existing literatures. This paper proposes a transaction model for key-value NoSQL databases including Redis to make possible allowing users to access data in the ACID (Atomicity, Consistency, Isolation and Durability) way, and this model is vividly called the surfing concurrence transaction model. The architecture, important features and implementation principle are described in detail. The key algorithms also were given in the form of pseudo program code, and the performance also was evaluated. With the proposed model, the transactions of Key-Value NoSQL databases can be performed in a lock free and MVCC (Multi-Version Concurrency Control) free manner. This is the result of further research on the related topic, which fills the gap ignored by relevant scholars in this field to make a little contribution to the further development of NoSQL technology.

面向云端Key/Value存储系统的开销敏感的数据迁移方法

Key/Value存储系统在大规模、高性能云应用支撑方面扮演了重要的角色,对云端Key/Value存储系统而言,数据迁移是实现节点动态扩展与弹性负载均衡的关键技术.如何降低迁移开销,是云服务提供商需着力解决的问题.已有研究工作大多针对非虚拟化环境下的数据迁移问题,这些方法对于云端Key/Value存储系统而言往往并不适用.为应对上述挑战,将数据迁移问题纳入负载均衡场景解决.提出一种基于面积的迁移开销模型,该模型可以有效感知底层VM性能干扰状况,权衡迁移时间与性能衰减值.进一步提出一种开销敏感的数据迁移算法,该算法基于开销模型与均衡度制订数据迁移计划,选取最优的迁移操作.基于雅虎的云服务基准测试工具YCSB验证了该方法的有效性.

基于操作历史图的分布式Key-Value数据库一致性检测算法

分布式数据库系统的副本机制在提高系统可靠性及性能的同时,导致了多副本数据管理的一致性问题;数据一致性的实现需要一致性协议模型来进行预防,也需要一致性检测算法对非一致数据进行检测。首先,对读写操作记录之间的时序关系、安全一致性及并行一致性原则等概念进行定义;其次,根据操作记录集合中读写操作之间的并行与时序关系,提取出操作记录集合向操作记录图转化的规则,并在此基础上设计了操作记录向历史记录图的转化算法;然后,以历史记录图为输入,设计了违反一致性查找算法,查找并返回图中所有违反安全与并行一致性读操作的集合;最后,基于Cassandra进行实验并将读写一致性设置为ONE,通过YCSB产生并行读写压力测试,与同类算法的对比实验验证了所提算法在功能与效率两方面的优越性。

一种基于裸闪存的Key-Value数据库优化方法

近年来,非关系型的key-value数据库得到越来越广泛的应用.然而,目前主流的key-value数据库或者是基于磁盘设计的,或者是传统的基于文件系统和闪存转换层FTL来构建的,难以发挥闪存存储设备的特性,限制了I/O的并发性能,且垃圾回收过程复杂.设计并实现了一种基于裸闪存的keyvalue数据管理架构Flashkv,通过用户态下的管理单元进行空间管理和垃圾回收,充分利用了闪存设备内部的并发特性,并简化了垃圾回收过程,去除了传统文件系统和FTL中的冗余功能,缩短了I/O路径.提出了基于闪存特点的I/O调度技术,优化了闪存的读写延迟,提高了吞吐率;提出了用户态缓存管理技术,降低了数据写入量和频繁系统调用所带来的开销.测试结果表明,Flashkv性能是levelDB的1.9~2.2倍,写入量减少60%~65%.

Key-value数据库在时序数据及互动信息处理中的分析应用

Key-value数据库在web2.0之后有了很大的发展。针对目前web2.0应用中关系型数据库存在的问题,通过对用户互动信息(例如,用户评论,打分,实时消息传递,微博数据等)的性能,可扩展性,高可用性上的特点的分析,提出了Key-value数据库在互动信息处理,时序数据处理方面的解决方案。

一个高性能Key/Value数据库XDB的设计与实现

传统SQL数据库在管理大数据、性能和扩展性等方面的不足使得其不能胜任如大规模数据挖掘、商务智能及社交网络等应用场景,而NoSQL数据库由于其在上述应用领域优良的特性近年来得到很快发展。本文在分析现有开源NoSQL数据库产品Kyoto Cabinet和Tair的不足基础上,设计并实现了一个高性能的Key/Value数据库XDB。XDB分段流水并发处理Key/Value请求,并采用一致性算法保证在并发环境中对Key/Value记录读写的相关性,在随机写入和顺序写入实验中,相比于Kyoto Cabinet,XDB的性能分别提高6倍和15倍。

一种基于key-value数据库的快速地名地址输入提示方法

现有地址输入提示方法涉及标准地址和POI的研究较少,地址字符串的索引大多采用Trie(字典)树索引,但Trie树建立时内存消耗巨大,在面临海量数据时,问题更加突出。针对以上问题,提出一种基于key-value数据库的快速地名地址输入提示方法。该方法基于Trie树结构进行改进,降低了地址索引的复杂度;基于keyvalue数据库构建Trie树,避免了内存消耗巨大的问题。实验结果表明,基于key-value数据库构建的Trie树索引较基于内存构建的Trie树索引在事务响应性能和内存消耗方面具有明显的优势和效率。

A MULTICAST KEY MANAGEMENT SCHEME BASED ON CHARACTERISTIC VALUES OF MEMBERS

A new collusion attack on Pour-like schemes is proposed in this paper. Then, we present a collusion-free centralized multicast key management scheme based on characteristic values of members. The re-keying method that other group members calculate new keys when a member is joining or leaving is also designed. It achieves forward secrecy and backward secrecy. Compared with typical existing centralized schemes, the storage of Group Key Controller (GKC) in our scheme halves the storage overhead of others, and communication overhead of GKC is 2 in case of joining re-keying. Especially, the leaving re-keying overhead is and the overall performance is excellent.

多核环境下Key-Value数据库性能分析与优化

在面对数据库高并发读写、高可扩展性和高可用性、海量数据的高效率存储和访问的需求下,传统的关系数据库显得力不从心,基于Key-Value的数据库应运而生。针对Key-Value数据库产品Memcached在单核、多核环境下的压力测试结果,在同种情况下多线程性能高于单线程、多实例性能高于单实例并充分利用系统资源。通过构建多核、多线程的Key-Value系统满足当前海量数据高效率存储和访问的需求。

改进的key/value数据存储设计方案

针对现有key/value缓存系统海量数据的访问速度慢,满足不了应用的需求,提出一种改进的key/value数据存储方案并将其应用于缓存系统中。通过小数据量存储方案的提出,及对rehash算法、rehash权重因子w的改进,十分有效地解决了hash冲突、rehash迁移数据导致的系统变慢问题,加快了缓存系统的速度,提高了缓存系统的命中率。

The Edible and Medicinal Value of <i>Coix lacryma-jobi</i>and Key Cultivation Techniques for High and Stable Yield

In this paper, it was introduced that Coix lacryma-jobi is a traditional dual-use edible and medicine crops in China, and the nutritional components and medicinal value of Coix lacryma-jobi were described. Based on the published literature at home and abroad, a variety of chemical components found in Coix lacryma jobi and their medicinal effects were reviewed. At the same time, the problems existing in the production of Coix lacryma jobi were put forward. With the improvement of people’s living standards, the nutritional and health care value of Coix lacryma-jobi has been paid more and more attention. The problems of Coix lacryma-jobi in production were analyzed. Some biological characteristics of Coix lacryma-jobi, especially its hygrophyte characteristics, were re-recognized, which is very important to increase the yield of Coix lacryma jobi. In the paper, the key cultivation techniques for high and stable yield of Coix lacryma-jobi were also summarized. In order to obtain high quality, high and stable yield, we should adopt the new technical methods of “two wet, two dry and two water” in water management. At the same time, if artificial pollination is applied in the peak of flowering period, the seed setting rate and the yield will be increased.

带有特征信息卷积神经网络的人脸识别算法

图像分类中,卷积神经网络在人脸识别中取得了较大的进展。在卷积提取人脸图像特征信息操作时,当卷积核数目有限的情况下,可能提取到的特征值,如头发、纹理等,并不能很好的代表该人的主要特征,从而导致识别率降低,而增加卷积核数目又会导致识别时间增加。针对这一问题,提出了一种基于特征信息卷积神经网络的人脸识别方法。该方法在图像处理过程中,使用奇异值分解,选取前4个奇异值代表人脸的主要特征,快速滤除大部分无用的特征信息,形成新的图像特征模板库。利用卷积网络在提高网络感受野的同时不丢失特征图信息的优势,融合最具有代表性的特征信息,最大程度地捕捉图像信息。采用卷积神经网络模型和基于奇异值分解的特征融合的结构模型实现人脸识别,仿真实验结果表明,这种方法减少了算法的训练时间,提高了人脸识别的准确性。

论“人民法院案例库”应用中的案件事实相似性判断

案件事实相似性判断是案例库应用中的重要基础性问题。案件事实相似性判断与裁判者视角立场相关、与法律争点交织、与案件事实相异性辨析相随,呈现复杂面相。实现案件事实相似性判断的客观定型需要遵循将案件事实区分为构成要件事实和非构成要件事实的路径。同时,应当重视价值评价的多元和复杂,通过将价值评价聚焦于立法精神实现客观化。当前案例库应用中存在案例应用动力不强、案例数量不足、案例应用目标不明、裁判文书说理欠缺等问题。为此,应当提升案例库应用认识自觉和方法指引;通过检察加入、信息化应用等方式加大案例资源供给;在案例库中试行标附文书,实现办案过程全景展现;同时建立效力异议等制度,强化推进案例库应用。

积极老龄化视域下老年教育发展路径探究

人口老龄化已成为世界性问题,老龄人口逐年递增以及随之而来的社会问题,要求我们必须将人口老龄化作为重要的议题来对待。在该视域下,老年教育的价值、功能、作用不断彰显。而积极老龄化的提出,顺应了该趋势,能够为我国老龄教育的现代化发展寻找到全新的切入点,推进老年教育事业健康、全面、快速、蓬勃发展。结合积极老龄化与老年教育的内涵,明确老年教育的必要性与发展问题,分别从国家、政府及教育机构的角度出发,探究老年教育的发展路径,以期应对人口老龄化问题,确保我国社会和谐、稳定地发展。

虚拟陈展中档案展品多价值维度的数据重构研究

虚拟陈展是对展览体系架构、信息传播形态以及场景内涵的多维度演变与转型升级。本文在探讨档案虚拟陈展的叙事本质基础上,阐述了虚拟展示空间内,基于档案展品的多种价值维度,探讨了档案数字展品的数据重组技术思路,并采用图数据库技术对展品内涵价值的“七要素”进行索引重构,确保档案虚拟陈展的叙述生态闭环。

基于价值链理念的培训项目管理信息系统的设计与研究

员工培训是企业人才培养的重要渠道,培训项目信息化程度决定了员工培训管理模式和整体质效,基于价值链理念的培训项目管理信息系统的设计,为培训企业构建了一个全生命周期、全流程管理的培训项目管理信息框架,对于打造培训项目数字化管理系统,规范资源管理,实现信息共享提供了实践范本。以企业党校培训项目信息系统建设实践为例,对基于价值链理念的培训项目管理信息系统设计进行重点阐述,为培训企业信息化建设提供创新实践参考。

计算机软件开发中数据库安全设计的应用研究

面对我国经济发展步伐的不断加快,各个行业都迎来了更多机遇,在这样的形势下,计算机发挥了重要作用,同时人们也对其安全性提出了更加严格的要求。技术人员十分关注计算机软件的设计,只有逐步强化软件的性能,才能满足当今社会对互联网环境的诸多要求。因此,本文围绕计算机软件开发中数据库安全设计的应用展开讨论,分析当前数据库开发的注意事项及测试问题,并结合一些数据,深入研究计算机软件开发中数据库安全设计的应用,可为相关人员提供一些借鉴。

云网一体化在教育行业的应用

文章提出一种将教育信息系统按应用、算力、存储资源分层解耦、云上部署的架构模式,配合入云网络的改造升级,实现突发、超大流量访问的有效承载、算力资源按业务匹配、数据资源统一供配。从而达到消除冗余信息,优质教育信息共享、共用,学情学况分级管控的目的。

Identification of key genes controlling cancer stem cell characteristics in gastric cancer

BACKGROUND Self-renewal of gastric cancer stem cells(GCSCs)is considered to be the underlying cause of the metastasis,drug resistance,and recurrence of gastric cancer(GC).AIM To characterize the expression of stem cell-related genes in GC.METHODS RNA sequencing results and clinical data for gastric adenoma and adenocarcinoma samples were obtained from The Cancer Genome Atlas database,and the results of the GC mRNA expression-based stemness index(mRNAsi)were analyzed.Weighted gene coexpression network analysis was then used to find modules of interest and their key genes.Survival analysis of key genes was performed using the online tool Kaplan-Meier Plotter,and the online database Oncomine was used to assess the expression of key genes in GC.RESULTS mRNAsi was significantly upregulated in GC tissues compared to normal gastric tissues(P<0.0001).A total of 16 modules were obtained from the gene coexpression network;the brown module was most positively correlated with mRNAsi.Sixteen key genes(BUB1,BUB1 B,NCAPH,KIF14,RACGAP1,RAD54 L,TPX2,KIF15,KIF18 B,CENPF,TTK,KIF4 A,SGOL2,PLK4,XRCC2,a n d C1 orf112)were identified in the brown module.The functional and pathway enrichment analyses showed that the key genes were significantly enriched in the spindle cellular component,the sister chromatid segregation biological process,the motor activity molecular function,and the cell cycle and homologous recombination pathways.Survival analysis and Oncomine analysis revealed that the prognosis of patients with GC and the expression of three genes(RAD54 L,TPX2,and XRCC2)were consistently related.CONCLUSION Sixteen key genes are primarily associated with stem cell self-renewal and cell proliferation characteristics.RAD54 L,TPX2,and XRCC2 are the most likely therapeutic targets for inhibiting the stemness characteristics of GC cells.

Using Multivalued Logic in Relational Database Containing Null Value

In this paper, several kinds of multivalued logic for relational database and their developing process are presented on the basis of null value's semantics. A new 5 valued logic is led into relational database containing null talue. The feasibility and necessity of using 5 valued logic are expounded. Comparative calculation and logical calculation under 5 valued logic are defined at the end of the paper.