Class: Cardinality

Inherits:

Object

• Object
• Cardinality

Defined in:

lib/nose/util.rb

Overview

Simple helper class to facilitate cardinality estimates

Class Method Summary

• .filter(cardinality, eq_filter, range_filter) ⇒ Fixnum

  Update the cardinality based on filtering implicit to the index.

Class Method Details

.filter(cardinality, eq_filter, range_filter) ⇒ Fixnum

Update the cardinality based on filtering implicit to the index

Returns:

• (Fixnum)

# File 'lib/nose/util.rb', line 170

def self.filter(cardinality, eq_filter, range_filter)
  filtered = (range_filter.nil? ? 1.0 : 0.1) * cardinality
  filtered *= eq_filter.map do |field|
    1.0 / field.cardinality
  end.inject(1.0, &:*)

  filtered
end