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Posted By

bordalix on 07/13/07


Tagged

performance counter cache column


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Counter Cache Column

Published in: Rails 

A great way to improve the performance of your web app, by using a column in the projects table which stores the number of task associated with it, seen in railscast #23

Plain TextExpand 
  1. class AddTaskCount < ActiveRecord::Migration
  2.   def seld.up
  3.     add_column :projects, :tasks_count, :integer, :default => 0
  4.     Project.reset_column_information
  5.     Project.find(:all).each do |p|
  6.       p.update_attribute :tasks_count, p.tasks.length
  7.     end
  8.   end
  9.  
  10.   def self.down
  11.     remove_column :projects, :tasks_count
  12.   end
  13. end
  14.  
  15. --
  16.  
  17. class Task < ActiveRecord::Base
  18.   belongs_to :project, :counter_cache => true
  19. end

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