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Object - Relational Database Orbase Inquiries And Optimize Processing

Posted on:2001-12-18Degree:MasterType:Thesis
Country:ChinaCandidate:Y Q XiaoFull Text:PDF
GTID:2208360002950981Subject:Computers and applications
Abstract/Summary:PDF Full Text Request
As the query standard of RDB(Relation Database), SQL(Structured Query Language) is extensive application, and it has profound influence on query language of Database. As the standard of QODB(Object-Oriented Database), OQL(Object Query Language) follows some important characters of SQL, and it cut apart the long path expression. In the ORDB(Qbject-Relation Database) prototype system ORbase developed by us, we express the nested relationship between objects by long path expression, which is clearly and explicitly. In ORbase, the query result retains the nested structure information. ORbase supports query computing of long path express with quantification, which is convenient for expressing semantic structure of Web data. QRbase can be used to implement managing and querying of Web by database technique. ORbase puts forward a query plan and optimization method for dealing with long path expression. In ORbase, there are two kinds of indexes for query optimization: one is path index, the other is grouping index. Because of existing aggregate attribute, there is quantification in long path expression. Dealing with the quantification in long path express is more difficulty. SQL transforms universal quantification into existing quantification. In OQL, universal quantification is forbidden to emerge in long path expression. ORbase gives a method for computing long path expression with quantification.
Keywords/Search Tags:query, long path expression, quantification, query optimization, index
PDF Full Text Request
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