OceanBase一致性与可用性分析

OceanBase作为一个面向海量数据查询的分布式数据库,支持关系查询和跨行跨表事务,同时保证了一致性和可用性.本文在详细阐述了一致性与可用性的背景基础上,根据传统数据库和分布式数据库保证一致性和可用性的协议和策略,对OceanBase的一致性和可用性架构进行分析.最后,探讨了基于OceanBase架构演变而来的3种架构的实现方案.     

OceanBase中基于布隆过滤器的连接算法

在大数据时代,"去IOE"运动的推进以及"双11"等活动的兴起对分布式数据库系统提出了更高的要求.OceanBase是阿里巴巴集团自主研发的开源分布式数据库,支持海量数据跨行跨表事务,但是对复杂查询的处理性能仍有待提高,其中连接操作带来的网络传输严重影响了数据库的性能.本文提出了一种基于布隆过滤器的连接算法,通过构建布隆过滤器对右表数据进行过滤,减少了不必要的数据传输开销,降低了数据处理带来的内存资源的消耗.本文在OceanBase上实现了该算法,并通过实验证明,该算法极大提高了连接操作的效率.     

分布式环境中数据库模式设计实践

近年来,数据规模呈爆炸式增长,使得传统集中式数据库难以满足业务需求.而分布式数据库可以将数据存储在多个节点上,具有更好的扩展性,从而可以支撑业务的不断增长.目前,许多企业已经开发出了成功的分布式数据库产品,例如Google Spanner、淘宝的OceanBase等.传统数据库模式设计中,三大范式(1NF、2NF和3NF)及其扩展范式能够减少数据冗余和更新异常,并保证数据的完整性.然而,在分布式架构下,严格遵循范式的模式设计可能带来查询效率较低等问题,而使用反范式模式设计方法通常可以有效提高查询效率.OceanBase是淘宝自主研发的分布式数据库,支持跨行跨表事务,并在OLTP中具有良好的性能,但是对于OLAP业务,其性能并不高.本文将以OceanBase为例,介绍如何利用反范式设计分布式数据库模式,以改善OLAP的查询性能,并通过在OceanBase上部署TPC-H基准评测验证了反范式模式设计的有效性和高效性.     

一种面向金融应用的海量分布式关系数据库

提出了一种面向金融应用的海量分布式数据库架构CBase,该架构融合了关系数据库和非关系型数据库的优点,既支持关系查询和跨行跨表的事务处理,又支持数据的分布式存储和节点的快速扩展.系统改进了现有分布式数据库单点故障的问题,具有较高的吞吐率和快速的响应时间,已经在银行业务中得到实际应用.实践证明:该数据库可满足金融业务对于大数据存储和查询的性能需求.     

面向OceanBase的存储过程设计与实现

存储过程是数据库管理系统的一个重要特性,它是标准结构化查询语言(Structured Query Language,SQL)的一个扩展.OceanBase是一个新型的支持海量数据处理的分布式数据库系统,但现有OceanBase的开源版本不支持存储过程功能,影响了该系统在企业和机构中的推广和应用.本文在深度分析存储过程原理以及OceanBase查询处理策略的基础上,设计并实现了支持PL/SQL(Procedural Language/SQL)的存储过程机制.     

面向OLAP应用的OceanBase模式设计

随着大数据时代的来临,用户查询需求也越来越复杂,对数据库的可扩展性和SQL查询效率都提出了很高的要求.OceanBase是Alibaba研发的适应互联网规模的关系型分布式数据库,能够做到可扩展、低成本、高可用,并能应用到很多业务场景,包括OLTP和OLAP.然而,当前发布的最新OceanBase只支持主键索引,还不能支持二级索引.其次,OceanBase在连接上没有并行处理,使得查询效率较低.因此,为了能够使用主键索引及减少连接来加快查询速率,OceanBase模式设计是必要的.本文主要以TPC-H的22个查询为OLAP的研究案例,分析传统数据库的模式设计,并提出OceanBase分布式数据库下的模式设计规则,最后将会通过实验来验证这套模式设计规则的有效性.     

SQL类查询语句的基本结构及其到关系代数表达式的转换

本文分析了SQL类查询语句的基本结构,指出任何一个嵌套结构的SQL类语句都可以由四种基本嵌套类型组成.在分析基础上,提出了将SQL类查询语句转换成关系代数表达式的算法.     

OceanBase关系数据库架构

传统关系数据库本质上是单机系统,通常采用昂贵的高端服务器和高端存储,难以应对互联网应用的高可扩展、高性能、高可用和低成本的挑战.OceanBase是阿里巴巴研制的开源分布式无共享关系数据库,采用主流通用PC服务器,很好地满足了互联网对关系数据库的需求.OceanBase已经用于淘宝、天猫和支付宝的多个生产系统.本文介绍了OceanBase关系数据库系统的架构、目标和系统特点,特别分析了基于该系统架构的读写事务流程.     

SQL类查询语句的基本结构及其到关系代数表达式的转换

本文分析了SQL类查询语句的基本结构,指出任何一个嵌套结构的SQL类语句都可以由四种基本嵌套类型组成。在分析基础上,提出了将SQL类查询语句转换成关系代数表达式的算法。关键词:查询语言,关系完备性,关系代数。     

关系数据库细粒度访问控制设计与实现

通过扩展SQL语句支持关系数据库细粒度访问控制(FGAC)策略的描述,扩展的SQL语句同时支持封闭式细粒度访问控制策略和开放式细粒度访问控制策略的描述,即支持细粒度的否定授权.给出了基于查询改写思想的动态查询改写算法,实现了细粒度访问控制,同时给出了细粒度访问控制实现框架,并在数据库管理系统(DBMS)中实现.实验验证了该实现方法的可行性.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with