Efficient implementation of full outer join and anti-join

Details Efficient implementation of full outer join and anti-join Efficient implementation of full outer join and anti-join

1997-06-25

1999-10-05

Black, Thomas G.

Data processing: database and file management or data structures

Database design

Data structure types

707 3, 707 4, 707 5, 707100, 707102, 707103, G06F 1730

Patent

active

059639334

ABSTRACT:
Method for specifying SQL "full outer joins" which enables the use of arbitrary join conditions in specifying the query. This is enabled by equating a full outer join with a left outer join unioned with a right outer join less the matched tuples from the right outer join. A number of embodiments further present improvements in execution speed. One such improvement utilizes as a second operand of the union query a novel operator, the "ANTI-JOIN". The anti-join is implemented as a right outer join coupled with an ISNULL predicate.

REFERENCES:
patent: 5412804 (1995-05-01), Krishna
patent: 5557791 (1996-09-01), Cheng et al.
patent: 5701454 (1997-12-01), Bhargava
patent: 5765159 (1998-06-01), Srinivasan
patent: 5797136 (1998-08-01), Boyer
"Hypergraph Based Reordering of Outer Join Queries With Compelx Predications", Gautam Bhargava, Piyush Goel & Bala Iyr, ACM 0-89791-731-6/95/0005, 1995, pp. 304-315.
"SQL Query Optimization: Reordering for a General Class of Queries", Piyush Goel & Bala Iyer, ACM 0-89791-794-4/96/0006, 1996, pp. 47-56.

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