Patents by Inventor Alex Chak-tsang Lui

Alex Chak-tsang Lui has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Evaluation of existential and universal subquery in a relational database management system for increased efficiency
    Patent number: 6032143
    Abstract: A relational data base management system includes a query processor that permits consideration of alternative query plans by the query optimizer so one table can be sent to a selected network location for subquery evaluation in consideration of maximum processing efficiency. Subqueries are converted from "predicate push-down" form to scalar subqueries, enabling upper tables to be sent to nodes of lower tables and vice versa, thereby permitting selection of the node direction depending on the least cost alternative. The optimizer of the query processor is presented with rewritten query code that permits more than one alternative for sending tables for evaluation. The optimizer evaluates the alternatives permitted by the rewritten code, determines the optimal plan for each alternative, and selects the least-cost plan from among the plans evaluated.
    Type: Grant
    Filed: December 4, 1998
    Date of Patent: February 29, 2000
    Assignee: International Business Machines Corporation
    Inventors: Ting Yu Leung, Alex Chak-tsang Lui, Mir Hamid Pirahesh, Tuong Chanh Truong
  • Evaluation of existential and universal subquery in a relational database management system for increased efficiency
    Patent number: 5864840
    Abstract: A relational data base management system includes a query processor that permits consideration of alternative query plans by the query optimizer so one table can be sent to a selected network location for subquery evaluation in consideration of maximum processing efficiency. Subqueries are converted from "predicate push-down" form to scalar subqueries, enabling upper tables to be sent to nodes of lower tables and vice versa, thereby permitting selection of the node direction depending on the least cost alternative. The optimizer of the query processor is presented with rewritten query code that permits more than one alternative for sending tables for evaluation. The optimizer evaluates the alternatives permitted by the rewritten code, determines the optimal plan for each alternative, and selects the least-cost plan from among the plans evaluated.
    Type: Grant
    Filed: June 30, 1997
    Date of Patent: January 26, 1999
    Assignee: International Business Machines Corporation
    Inventors: Ting Yu Leung, Alex Chak-tsang Lui, Mir Hamid Pirahesh, Tuong Chanh Truong