The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 27, 1999
Filed:
Oct. 16, 1997
Guy M Lohman, San Jose, CA (US);
Bernhard Schiefer, Scarborough, CA;
Monica S Urata, Los Gatos, CA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A join optimizer and method for a relational database management system including a data processor, a stored database, and a plurality of database relations, wherein one or more of the relations are retrieved by the processor by means of query commands by performing a plurality of join operations on the relations, the system employing a general purpose heuristic algorithm which excludes or defers Cartesian products as late in the join sequence as possible, the method includes the steps of determining, in association with the execution of, or preferably prior to executing the general purpose algorithm, whether tables referenced in a query command includes a hub table and at least two encoding tables related to the hub table and, when the query command references a hub table and at least two encoding tables, determining the best access plan for the hub table, determining whether the best access plan utilizes an index used to access the hub table and, if so, constructing a plan to join the encoding tables as Cartesian products, constructing a plan to join the hub table and the encoding tables and storing the plans in the data structures of the optimizer for enumeration with other access plans constructed by the optimizer.