Performance of program modification techniques that ensure serializable executions with snapshot isolation DBMS

Snapshot Isolation (SI) is a multiversion concurrency control that has been implemented by several open source and commercial database systems (Oracle, Microsoft SQL Server, and previous releases of PostgreSQL). The main feature of SI is that a read operation does not block a write operation and vice versa, which allows higher degree of concurrency than traditional two-phase locking. SI prevents many anomalies that appear in other isolation levels, but it still can result in non-serializable executions, in which database integrity constraints can be violated. Several techniques are known to modify the application code based on preanalysis, in order to ensure that every execution is serializable on engines running SI. We introduce a new technique called External Lock Manager (ELM). In using a technique, there is a choice to make, of which pairs of transactions need to have conflicts introduced. We measure the performance impact of the choices available, among techniques and conflicts.     

基于C#实现SQL Server和Oracle数据库间数据迁移

该文分析SQL Server和Oracle数据库间数据迁移的现有技术、方法后,提出采用C#编程并以ADO．NET技术分别来访问这两种数据库,进而设计一个数据迁移程序,实现此两种数据库互相迁移数据。     

基于日志的数据库更新通用外部监测方法

提出了一种通用的利用各类数据库提供的日志功能,通过读取和分析日志记录来进行数据库更新外部监测的方法,并初步实现了一个通用的数据库更新外部监测器,能够对Oracle9和SQLServer2000数据库进行数据更新监测。     

基于SQL Server的SQL注入攻击防范方法

在基于SQL Server服务器的Web应用程序中,确保安全性是一个重要而复杂的问题。该文针对SQL Server数据库的安全性,介绍了SQL注入攻击概念及几种常用的攻击方法,从两个方面提出了一些防范SQL注入攻击方法,最大限度地减少SQL注入攻击的可能性,尽可能保证SQL Server数据库的安全性。     

试论在Authorware中如何进行数据库操作

随着数据库技术的发展。在Authorware制作中经常会遇到一定的数据库操作．如“函数变量速查”查询系统的设计就涉及到数据库操作。利用Authorware提供的ODBC接口．多媒体教学课件的制作及开发者就可以很方便地操作数据库。由此可以大大增强Authorware的多媒体开发制作功能。在Authorware中使用ODBC接口和标准的SQL语言即可对Access、Foxpro、Oracle、SQL Server等数据库中的表进行查询、添加、删除、更新等基本操作了。     

Planning and Implementing Kerberos for Large Distributed Systems Part 1

ABSTRACT

For maintaining the consistency of database, the recovery algorithms traditionally depend on complete rollback to a consistent checkpoint. The recovery problem from committed malicious transactions can be solved by determining the dependencies between the transactions in window of vulnerability. Since the size of transactional log may grow very large, recovery becomes a complex and time-consuming process. In this paper, we propose an approach which incorporates application specific information to determine transactional dependencies. The approach is applied to column based transaction dependency to obtain better performance. The system is implemented at application layer where SQL queries are generated. In recovery phase, we consider only affected and malicious transactions for rollback and skip the good transactions.     

广东省气象短信推广数据分析程序设计

为了推广气象短信的应用,经常需要分析用户数据用于群发,或提取部分或全部数据用于与运行商稽核。这涉及到复杂的SQL语句编写和大数据量的导入导出,大部分的功能比较单一且重复。广东省气象短信的定制用户已经是达千万量级,短信系统需要采用能快速导入导出大批量数据的技术。为此,采用复杂的组合选择技术自动生成SQL语句,由数据库完成数据比对和提取工作;针对目前气象短信Oracle和SQL Server数据库并存的现状,提出了不同的导入导出数据的解决方案。该方案中,Oracle采用SQL＊LOADER和SQL＊UNLOADER导入导出数据,SQL Server采用DTS技术,程序采用Delphi开发。     

A column dependency-based approach for static and dynamic recovery of databases from malicious transactions

Even state of the art database protection mechanisms often fail to prevent occurrence of malicious attacks. Since in a database environment, the modifications made by one transaction may affect the execution of some of the later transactions, it leads to spreading of the damage caused by malicious (bad) transactions. Following traditional log-based recovery schemes, one can rollback (undo) the effect of all the transactions, both malicious as well as non-malicious. In such a scenario, even the unaffected transactions are also rolled back. In this paper, we propose a column dependency-based approach to identify the affected transactions which need to be compensated along with the malicious transactions. To ensure durability, committed non-malicious transactions are then re-executed in a manner that retains database consistency. We present a static recovery algorithm as well as an on-line version of the same and prove their correctness. A detailed performance evaluation of the proposed scheme with TPC-C benchmark suite is also presented.     

基于C API的MySQL数据库多线程访问方法

目前,数据库在各行各业中广泛应用.在众多商业数据库软件中,SQL SERVER和ORACLE被较多的使用,因此这两个数据库软件的价格也较昂贵.本文主要介绍MySQL数据库在单线程或多线程程序环境下使用C API访问MySQL数据库方法,并给出了相应代码和分析.该数据库属于开源数据库,具有较高的成熟度,并且对于社区版本可以免费使用,因此对于需要使用C API访问数据库的项目开发,可降低开发成本.     

基于SQL和ADO的用户数据库自动部署

现有安装程序（如Installsheild、InstallFactory等）在解决用户数据库的自动部署时,操作步骤非常复杂和繁琐,不易掌握和使用。针对这一问题,提出了利用SQL和ADO编程来实现用户数据库的自动部署的方法。该方法对于大多数数据库管理系统（如SQL Server、Oracle、Sybase、DB2等）具有通用性;并且没有编程语言的限制,对VC、VJ、VB、Delphi等都适用,使用简便,具有较高的实用性。     

Recovery from malicious transactions

Preventive measures sometimes fail to deflect malicious attacks. We adopt an information warfare perspective, which assumes success by the attacker in achieving partial, but not complete, damage. In particular, we work in the database context and consider recovery from malicious but committed transactions. Traditional recovery mechanisms do not address this problem, except for complete rollbacks, which undo the work of benign transactions as well as malicious ones, and compensating transactions, whose utility depends on application semantics. Recovery is complicated by the presence of benign transactions that depend, directly or indirectly, on the malicious transactions. We present algorithms to restore only the damaged part of the database. We identify the information that needs to be maintained for such algorithms. The initial algorithms repair damage to quiescent databases; subsequent algorithms increase availability by allowing new transactions to execute concurrently with the repair process. Also, via a study of benchmarks, we show practical examples of how offline analysis can efficiently provide the necessary data to repair the damage of malicious transactions.     

基于SQL Server 2000的通用模糊查询工具设计

本文设计并实现了一个基于SQL Server 2000的通用模糊查询工具,该工具可以把带权重的模糊查询转换为标准的SQL语句。用户可以对SQL Server中建立的任何数据库表进行模糊查询。系统提供了以下功能：定义模糊谓词及其隶属函数;定义模糊算子;构造带权重的模糊的、精确的或混合的查询语句,权重和阈值可以由用户给出。满足查询条件的记录将根据匹配度的降序输出。本系统的设计方法也可以推广到其他的数据库系统,如Oracle,Access等。     

Oracle分布式数据库及其应用研究

介绍分布式数据库系统的概念,阐述了Oracle分布式数据库系统和Oracle高级复制系统的体系结构、优缺点及相关应用。具体说明了Oracle和MS SQL Server构成异类分布式数据库系统的创建方法。给出了一种基于Oracle数据库分布式应用架构的电子政务解决方案。     

X-Base PL/SQL异常处理的设计与实现

X-Base PL/SQL是一种过程式数据库编程语言,常用于数据库服务器端应用程序的开发。该文讨论了X-Base PL/SQL引擎中异常处理模块的设计思想和实现技术。鉴于Oracle数据库管理系统是数据库产品事实上的标准,还有其在全球的广泛应用,X-Base PL/SQL需要兼容Oracle PL/SQL 8i的异常处理机制。     

基于XML的商业DBMS技术评述

XML已成为Web上数据表示与交换的标准格式。在需求与技术的驱动下，各数据库厂商纷纷推出了XML－Enabled产品。介绍并评述了目前3种主要的商业DBMS（Oracle8i,DB2,SQL Server2000)对XML进行的功能扩展。     

应用程序中数据库备份与恢复的实现

针对Oracle,SQL Server,Sybase数据库,分别在C／S和B／S体系结构的应用程序中实现了数据库的备份与恢复,使用户在应用程序的客户端即可方便地实现对数据库的备份和恢复操作。     

Java连接数据库SQL Server 2005

Java是全球使用广泛的一门网络编程语言,当今许多系统都是用Java语言进行编写的;SQL Server 2005是Microsoft公司推出的大型数据库系统,现在在一些大中型系统中有着广泛的使用,它的编程接口非常丰富、易用,提供了JDBC编程接口。在基于Java的软件系统中通过加载JDBC驱动和相关jar包,既可以实现在Java编程中连接SQL Server,也可通过连接池来连接SQL Server数据库。     

基于SQLServer数据库安全机制问题的研究与分析简

SQLServer是一种数据库管理系统,它是为了分布式客户机／月艮务器所设计的,是一种高性能的数据库管理系统。由于SQLServer的应用非常广泛,如何保证SQLServer数据库应用程序的安全问题成为一个技术研究方向。本文深入浅出地介绍SQLServer数据库,分析SQLServer数据库的安全机制,介绍SQLServer有哪些安全设置及其如何部署配置。     

SDriver: Location-specific signatures prevent SQL injection attacks

SQL injection attacks involve the construction of application input data that will result in the execution of malicious SQL statements. Many web applications are prone to SQL injection attacks. This paper proposes a novel methodology of preventing this kind of attacks by placing a secure database driver between the application and its underlying relational database management system. To detect an attack, the driver uses stripped-down SQL queries and stack traces to create SQL statement signatures that are then used to distinguish between injected and legitimate queries. The driver depends neither on the application nor on the RDBMS and can be easily retrofitted to any system. We have developed a tool, SDriver, that implements our technique and used it on several web applications with positive results.     

消除同音查询的死角——汉语言文字多音同音查询解决方案

本文通过分析汉语言文字“读音-字形”之间的“多-多”对应关系,阐明了现有数据库同音查询技术中因忽视多音字问题而导致漏查的缺陷,提出了以汉字字形输入代替拼音字母输入,同时在查询逻辑上加以扩展和改造,从而弥补上述缺陷,实现汉语言文字多音同音查询的完整解决方案。此外,本文试图通过对本方案的扩展及延伸,从汉语言文字问题推导出方言、译音、乃至其它种类语言文字类似问题的解决思路,进而为发掘事物的内在联系、发展人工智能提供参考。