ibis::query::weight Class Reference

A class to be used for reordering the terms in the where clauses. More...

#include <query.h>

Inheritance diagram for ibis::query::weight:

Public Member Functions
virtual double	operator() (const ibis::qExpr *ex) const
	Generate a weight based on estimated query processing costs. More...
	weight (const ibis::part *ds)

Detailed Description

A class to be used for reordering the terms in the where clauses.

Member Function Documentation

double ibis::query::weight::operator() ( const ibis::qExpr *  ex ) const

virtual

Generate a weight based on estimated query processing costs.

This function produces consistent result only for operators AND and OR. It assumes the cost of evaluating the negation to be zero.

Implements ibis::qExpr::weight.

References ibis::part::estimateCost(), ibis::qExpr::getLeft(), ibis::qExpr::getRight(), ibis::qExpr::getType(), ibis::part::nRows(), ibis::part::patternSearch(), and ibis::part::stringSearch().

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The documentation for this class was generated from the following files:

• query.h
• query.cpp