Patent ID: 6032143
Filing Date: 2000-02-29
Classification: G06F,Y10S

Abstract:
A method of optimizing and processing a query in a relational database management system that operates in a computer network and processes the query to retrieve data from computer storage, the method comprising:receiving a query containing a subquery such that one or more columns of the tables in the query are compared with one or more columns of the tables in the subquery, the tables in the query being partitioned on a first set of nodes of the computer network and the tables in the subquery being partitioned on a second set of nodes of the computer network;rewriting the query into an equivalent query;generating a first alternative query plan, based on the rewritten query, for performing the comparison of table columns at the first set of nodes of the computer network;generating a second alternative query plan, based on the rewritten query, for performing the comparison of table columns at the second set of nodes of the computer network; andselecting one of a plurality of alternative query plans for processing the query, the plurality of alternative query plans including the first alternative query plan and the second alternative query plan.