Research And Implementation Of Query Planning System For Information Integration Application

With the rapid development of Network Technology and Database Technology, Huge amount of datas distribute in different business systems in a big enterprise. Researchers have to confront with the problem that how to well gather and quickly integrate information from different data sources, and it's the essential mission for Information Integration Technology to provide users with uniform user interfaces of heterogeneous data source.To solve the problem of heterogeneous information access, and realize the data sharing in and between enterprises, this paper researches heterogeneous data integration system based on the Mediator/Wrapper architecture and focuses on some issues in query processing, including: query analysis, query rewriting, query decomposition and other related issues. Then a query planning system is designed and implemented. This query planning system has two components: Query Analyzer and Query Rewriter. Based on research of Parser Generator Technology, Query Analyzer as a flexible SQL query compiler, implements Lexical Analysis,Syntactic Analysis and Semantic Analysis. Query Rewriter rewriters the condition expression first, than recording to different need of different DDL sentence, translate global schema to import schema equivalently. Finally a query decomposition algorithm referring to query capacity of wrapper is proposed.This algorithm makes full use of wrappers to perform selection, projection, join, aggregation and grouping operations to reduce the transmission of subquery results.