Patent ID: 6438542
Filing Date: 2002-08-20
Classification: G06F,Y10S

Abstract:
A method of optimizing a query in a computer system, the query being performed by the computer system to retrieve data from a database stored on the computer system, the method comprising the steps of:(a) analyzing the query in the computer system to identify any joins therein that are lossless by partitioning the joins into lossless and lossy joins, and to identify any tables of the identified joins that are eligible for removal, wherein the partitioning step comprises partitioning the tables of the joins according to their associated quantifiers, each of the quantifiers has a quantifier state indicating whether the table participates in a join that is lossless, and the quantifier states are selected from a group comprising: a PS state indicating a potentially single state, a S state indicating a single state, and an N state indicating a lossy state; and (b) rewriting the query in the computer system to eliminate the identified tables.