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Research Of Query Rewriting And Multi-join Query Optimization Based On GA Of Database

Posted on:2009-12-15Degree:MasterType:Thesis
Country:ChinaCandidate:L Y GuoFull Text:PDF
GTID:2178360308479121Subject:Computer application technology
Abstract/Summary:PDF Full Text Request
Query optimization is an important technique for designing and implementing database management system (DBMS). It is a crucial factor that affects the capability of database. At present, this technique is successfully applied in all commercial databases. The great success of relational database and SQL mainly benefits from the development of query optimization technology. Searching an optimized executive strategy for every complex query is the key of success for database development. In database field, it is still an N-P problem. In the process of query, ineffective SQL, shortage of statistics and incorrect join order are all the reasons for lowering the query rate. Based on the statistics dictionary and the model, the query optimization is to rewrite the ineffective SQL and select the best join order for multi-tables.According to the factual problem of query efficiency in Criminal Interrogation assistance decision support system, this paper discusses a series of essential query optimization problems. Such as "automating statistics management for query optimizers", "rewriting the SQL statement based on statistics".The paper also takes aim at the problem of the efficiency many-join-query, Present an improved Genetic Algorithm. In addition, we make some key discussions on realization of query optimization. By some tests, we proved that the model of the based-statistical query optimizer is feasible; The improver GA has obvious advantages in the process of dealing with many-join-query.
Keywords/Search Tags:Query optimization, Query rewriting, Database statistics, Combinatorial optimization, Genetic algorithm
PDF Full Text Request
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