Reordering of complex SQL queries involving GROUPBYs, joins, out

Details Reordering of complex SQL queries involving GROUPBYs, joins, out Reordering of complex SQL queries involving GROUPBYs, joins, out

Filed on

1997-08-01

Date issued

1999-02-23

Examiner

Kulik, Paul V.

Patent Class

Data processing: database and file management or data structures

SubClass

Database design

SubSubClass

Data structure types

Other Related Categories

707 2, G06F 1730

Type

Patent

Status

active

Patent number

058754474

Description

ABSTRACT:
A method, apparatus, and article of manufacture for query simplification by applying generalized inference propagation and generalized transitive closure in SQL queries having selection, projection, join, outer join, and intersection operations. The disclosed transformations and enumeration method unify and solve the problems of 1) unnesting join aggregate queries, and 2) complete enumeration of queries containing outer joins, when the outer join predicate references an aggregated value, or the predicate references more than two base relations in a query subtree. The system first eliminates redundant sub-expressions and modifies expensive binary operations to inexpensive binary operations, then converts complex predicates to simple predicates by application of a generalized selection (GS) operator.

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Gautam Bhargava et al., "Efficient Processing of Outer Joins and Aggregate Functions", 1996, 12th International Conference on Data Engineering, IEEE, pp. 441-449.
Pintsang Chang, "Nonlinear Versus Linear Recursion: A Perspective from Computing Transitive Closure of a Binary Relation by the Join Domain Nested Loops Approach", 1990, Compsac, pp. 382-390.

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