| 1. | Concentrative db has not satisfied human ' s need and distributed db occupies the new stage
集中式数据库已经不能满足人们的需求，分布式数据库走入了当今的舞台。 |
| 2. | It is a very active research area in distributed database systems . there is difference between centralized database and distributed database , which distributed database needs data transportation
由于集中式数据库和分布式数据库的区别在于，分布式数据库需要站点间的数据传输。 |
| 3. | Because distributed database system is not the simple combination of internet and database system , it is difficult to realize and there is not real distributed database system for commercial use now
由于分布式数据库系统并不是网络技术与集中式数据库系统的简单结合，它的实现难度极大，现今还没有真正的商用分布式数据库系统。 |
| 4. | Classification based on distributed ecl is proposed in the dissertation , the improvements in time and complexity are expected . the promising approach can be used for centralized databases as well as distributed databases
这种方法不仅适用于大规模的集中式数据库，同时也能用于处理异构、分布式的数据库，具有很好的研究前景。 |
| 5. | The better way to avoid maintenance problems is to cache the wsdl in the centralized database and then periodically check the timestamp version number of the wsdl to see if a newer one is available
为避免维护上的麻烦，更好的一个办法就是把wsdl高速缓存在一个集中式数据库里，然后定期检查它的时间戳记/版本号，看看是否有一个更新的wsdl可用。 |
| 6. | In addition , distributed database system contains more complex contents than centralized database system . this essay aims to research on the principle , design and realization technology of oracle distributed database system
另外，在查询处理、事务管理、数据的完整性与安全性等方面，分布式数据库系统比集中式数据库系统具有更复杂、更丰富的内容。 |
| 7. | Distributed database is the production that was combined by the computer network and the database technology . it is a new field of database technology . distributed database system has new way to manage the numbers and save them in which the normal database and the c / s ( client / server ) has not
分布式数据库是数据库技术和计算机网络技术相结合的产物，是数据库技术的一个新领域，分布式数据库系统( ddbs )具有集中式数据库和c s (客户机服务器)不具备的数据的存储和处理方式。 |
| 8. | As the application of distributed computing is used much more widely ， distributed database becomes a significant part of information management it avoids a lot of disadvantages of conventional centralized database ， and is applicable to many situations distributed database is a set of data which is the unity logic ， but in fact these data is located on different sites it is of high availability ， easy expansibility ， high concurrency ， high efficiency and etc in distributed system ， data redundancy is a method to improve the speed of query and the availability of system distributed query should shield the lower level details of data redundancy from end users ， distributed transaction should ensure data from disaccord this paper introduces basic conceptions of distributed database firstly ， discusses distributed transaction and concurrent control ， describes the development prototype mysql ’ s characters ， architecture and executive mechanism ， then shows the skeleton model of dpsql and exposes the strategy and algorithm of distributed query and distributed transaction ， at last analyzes the extra expenses and response delay of distributed processes this paper exposes the implementation mechanism of distributed query and distributed transaction emphatically distributed query uses the strategy of “ read one ， write a11 ” s0 in such a system if user ’ s requests are read - - only for the most part and the distribution of data redundancy is plausible ， efficiency is very high distributed transaction uses two - 。 phase commit protocol to ensure the consistency of global data ， which has less communication overhead
分布式查询需要向用户屏蔽数据冗余分散的底层细节，分布式事务处理要保证全局数据完整，这都是传统集中式数据库不曾面临的问题。本文首先介绍了分布式数据库的概念性问题；接着讨论了分布式事务涉及的定义及算法；然后描述了dpsql的原型mysql的特性、结构和执行机制；继而给出了dpsql的梗概模型，阐述了实现分布式查询和分布式事务处理的策略及算法；最后分析了进行分布式处理给系统增加的额外开销和客户端的额外响应延迟。本文重点描述了分布式查询和分布式事务处理的实现机制，分布式查询采用”读一个写全部”的本地优先策略，在读操作频繁的系统中，只要库的分布合理，单机效率极高，几乎无任何附加开销和延迟，而以整个系统的角度看来，吞吐量就更是优于单机系统；分布式事务处理采用两阶段提交协议，通信次数较少并能确实保证副本一致。 |
| 9. | Distributed database technology is the integration of database technology and computer network technology . apart from the characteristics of centralized database such as data logical independence and physical independence , it has its own unique characteristics such as distributed independence of data . it has to consider not only the self - government of local places , but also the logical integrity of the whole database
分布式数据库技术是数据库技术和计算机网络技术的结合，它除了具有集中式数据库所具有的特点外，还具有它自己独有的特点：它不但要考虑局部场地的自治，而且要解决全局数据库的逻辑整体性；它除了具有集中式数据库所具有的数据逻辑独立性和物理独立性，还具有数据的分布独立性。 |
