Teradata Us, Inc.

Ming Zhang

Sanjay Nair

Grace Kwan-On Au

Mohammed Hussien Al-Kateb

Conrad Tang

An apparatus, method and computer program product for query optimization in a Relational Database Management System (RDBMS), wherein an optimizer accesses a query expression repository (QER) storing planning and execution information for QEs from previous queries, wherein the QEs comprise table relations, intermediate results and/or final results of operations in the previous queries. Additionally, dynamic join indexes representing QE results are created for high-value QEs selected from the QER and maintained within a DJI repository. During query plan creation for a current or subsequent query, the optimizer searches the QER and DJI repository for DJIs created for high-value QEs corresponding to QEs contained in the current or subsequent query. DJIs corresponding to the matching QEs are used in the query planning phase to rewrite the current or subsequent user query so that stored QE results are used to answer QEs contained in the current or subsequent query.

Query expression result caching using dynamic join index

A method, apparatus, and computer program product for executing a relational database management system (RDBMS) in a computer system, wherein the RDBMS manages a relational database comprised of one or more tables storing data. The RDBMS executes a query with a semi-join operation comprising an inclusion join and/or an exclusion join performed against at least an outer table and an inner table, wherein the inclusion join returns a row from the outer table when there is a match with a row in the inner table, and the exclusion join returns a row from the outer table when there is no match with a row in the inner table. The RDBMS performs a rewrite of the query to avoid spooling and/or sorting of the inner table, when the inner table is larger than the outer table and a cost after the rewrite is lower than before the rewrite.

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Rolling Hills Estates, CA, United States of America

Ming Zhang