Invention Grant
- Patent Title: Processing a sequence of outer joins
- Patent Title (中): 处理一系列外连接
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Application No.: US12639380Application Date: 2009-12-16
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Publication No.: US08688722B1Publication Date: 2014-04-01
- Inventor: O. Pekka Kostamaa , Yu Xu
- Applicant: O. Pekka Kostamaa , Yu Xu
- Applicant Address: US OH Dayton
- Assignee: Teradata US, Inc.
- Current Assignee: Teradata US, Inc.
- Current Assignee Address: US OH Dayton
- Agency: Trop, Pruner & Hu, P.C.
- Agent Ramin Mahboubian
- Main IPC: G06F7/00
- IPC: G06F7/00 ; G06F17/30

Abstract:
To process a sequence of outer joins in a database system, the database system performs a first outer join of the sequence of outer joins. A result of the first outer join is stored in a result table stored across plural storage modules of the database system. At least a subset of records of the result table is redistributed across the storage modules according to a first join attribute of the result table, where any record of the result table that has a null value for the first join attribute is not redistributed. A second outer join of the sequence is performed using the redistributed result table and another table, where the second outer join is based on the first join attribute of the result table.
Information query