Research On Query Optimizing In Distributed Database

Database technology that began in 1960s has become one of important technologies of computer applications after 30 years of development. For the application range of database technology itself, database application systems of all sizes and uses have been put into use and the new database application systems are increasing. In the depth and breadth of its application, other branches of the computer field can not be compared. For the research and development of the database technology, the cross-penetration between various disciplines and database technology has resulted in many new database technologies. In 1980s, the relational database and its associated various data modeling tools, indexes, data organization technology, etc, became more mature, and some relational database management software and some auxiliary tools improved continuously. The leading companies in the database field, such as Oracle Corporation, have successfully applied some research results and technologies of the some core relational database to their products. Since the mid-1980s, the integration of relational database technologies and new technologies has become an important symbol of the database development and research. With the development of wireless technology and network technology development, particularly since the establishment of "WWW" (World Wide Web), the distributed database technology has been adequately researched and some technical and theoretical issues have become clear, and become one of mainstream technologies in the database family.This paper has made a full analysis and research on the distributed database technology, especially on the query optimization technology of the distributed database, and proposed the query optimization algorithm, based on the previous studies to solve the corresponding problems. The main contents of the paper include the following aspects:Firstly, this paper made an analysis and research on the distributed database and its query optimization. The paper introduced the basic concept of distributed database, classified, summarized the process and common technologies of query optimization, and made an analysis on the domestic and foreign research status of the distributed database technology.Secondly, this paper presented a thorough study of various strategies and algorithms of distributed query optimization, with the communication transmission costs as the main optimization object, adopted semi-connection technology to optimize the distributed query, and proposed a predictive in advance optimization algorithm based on the semi-connection technology and a variety of real-time parameters. For the corresponding processing of some parameters in the formula, we should not only take local delay costs into account but also the communication costs between sites, which owns a more practical value in the field of complex queries of distributed database and massive information query.Thirdly, the paper also adopted the parallel processing strategy, proposed a distributed query optimization algorithm based on the direct connection, which reduced the connection costs, lowered the communication costs and effectively reduced the query response time.