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Query Optimization Research Of Analysis Database And Its Implementation

Posted on:2010-02-13Degree:MasterType:Thesis
Country:ChinaCandidate:R LiFull Text:PDF
GTID:2178360272496684Subject:Software engineering
Abstract/Summary:PDF Full Text Request
National defense and economic development are an urgent call for China to have a general relational database system which with an autonomous copyright, with the basic functions of a relational database system, is able to support the application of computer networks and data storage applications, while at the same time have a higher level of security. At the same time in order to meet the market requirements of the speed of database queries, South universal upgrade the prototype of its database products and develop an analysis using of commercial relational database management system with their own intellectual property rights– Gbase 8a.The current relational database systems allow user to complete the complex operation on the database through SQL statement. Database query is the most basic and commonly used in an operation, therefore, whether a higher query performance and faster response speed, has become an extremely concern database users and designers. In order to improve the performance of database systems, query optimization is essential that the success of the existing large commercial database systems to a large extent should be attributed to the development and application of query optimization technology.In this paper, we first analyze the status of query optimization technical studies at home and abroad, introduce the database query optimization techniques and the main contents of query optimization and query optimization process, and through examples to describe the importance of query optimization in database management system. Immediately following the introduction of the relational database query optimization principles and the design process, based on a further study of query optimization introduce a complete set of schema to implement query optimization module in the relational database, and consider the GBase 8a database, give some of the important modules and functions to achieve the query optimizer, and discuss the related issues to implement Query Optimizer.Then introduce the implementation of GBase 8a database query optimizer. The first is query rewriting module, put forward a complete set of query rewriting rules, including the equivalent predicate rewriting and sub-query rewriting, focuses on a series of equivalence predicate rewriting rules, and applied query optimization module to GBase 8a. At the same time, in order to facilitate the management to rewrite rules, we have adopted a scalable, plug-in rules engine of query rewrite to rewrite the rules for the administration, so that users can be used to control rules of query rewriting. Then, the hash algorithm is applied to query optimization in relational databases, if used directly, because of the impact of memory failure, the speed is not very satisfactory, so according to the characteristics of our modern computer storage of the class structure, Proposed a blocked hash join algorithm block (partition-join), first put the relationship into a small block using some rules, and then on the corresponding block for the connection, final put outcome together. Here the most important is sub-block algorithm (radix-cluster) and the hash join algorithm, for those who do not use hash connections but comparison each value repeating, for sub-block is also used to connect the idea, we also use the idea of blocking In this way we also achieve an alternative partition-join, algorithm (radix-join), in the process of GBase 8a, GBase 8a will parse the SQL statement into a sequence of the implementation body (a collection of execution), between these instructions they are probably independent, and probably dependent with each other. So according to the characteristics of many modern computer with multi-CPU and multi-core, use multi-threaded parallel technology, send a collection of execution in which the instructions are independent of each other to parallel execute, this will make full use of the advantages of multi-core, improve query performance.After many experiments, results show that the proposed query optimization solutions are feasible, the optimization algorithm-related effects is quite obvious. But the rush to do so, only focus on the research and implementation of predicate rewritten, not being able to get some more reasonable rewrite rules, and did not consider the use of query plans (QGM) to conduct a study of the query rewriting. In aspects of query optimization algorithms, in this paper only preliminary discussions not able to make deeper studies.Finally, through the TPCH benchmark, comparative analysis of different aspects, introduce the database performance situation after the use of query optimization in detail.
Keywords/Search Tags:Relational databases, query optimization, query rewriting, parallel processing, partition-join
PDF Full Text Request
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