setup relations in models + indexes on foreign keys

app/models/checkout.rb

@@ -1,2 +1,4 @@
 class Checkout < ActiveRecord::Base
+  belongs_to :users
+  belongs_to :medias
 end

app/models/downloads.rb

@@ -1,2 +1,4 @@
 class Downloads < ActiveRecord::Base
+  belongs_to :users
+  belongs_to :medias
 end

app/models/item.rb

@@ -1,2 +1,3 @@
 class Item < ActiveRecord::Base
+  has_many :medias
 end

app/models/media.rb

@@ -1,2 +1,5 @@
 class Media < ActiveRecord::Base
+  belongs_to :items
+  has_many :checkouts
+  has_many :downloads
 end

app/models/user.rb

@@ -1,2 +1,4 @@
 class User < ActiveRecord::Base
+  has_many :checkouts
+  has_many :downloads
 end

db/migrate/20091221013559_add_keys_to_media.rb

@@ -1,9 +1,11 @@
 class AddKeysToMedia < ActiveRecord::Migration
   def self.up
     add_column :medias, :item_id, :integer
+    add_index :medias, :item_id
   end
 
   def self.down
     remove_column :medias, :item_id
+    remove_index :medias, :item_id
   end
 end

db/migrate/20091221013631_add_keys_to_checkout.rb

@@ -2,10 +2,14 @@ class AddKeysToCheckout < ActiveRecord::Migration
   def self.up
     add_column :checkouts, :user_id, :integer
     add_column :checkouts, :media_id, :integer
+    add_index :checkouts, :user_id
+    add_index :checkouts, :media_id
   end
 
   def self.down
     remove_column :checkouts, :media_id
     remove_column :checkouts, :user_id
+    remove_index :checkouts, :user_id
+    remove_index :checkouts, :media_id
   end
 end

db/migrate/20091221013657_add_keys_to_downloads.rb

@@ -2,10 +2,14 @@ class AddKeysToDownloads < ActiveRecord::Migration
   def self.up
     add_column :downloads, :user_id, :integer
     add_column :downloads, :media_id, :integer
+    add_index :downloads, :user_id
+    add_index :downloads, :media_id
   end
 
   def self.down
     remove_column :downloads, :media_id
     remove_column :downloads, :user_id
+    remove_index :downloads, :user_id
+    remove_index :downloads, :media_id
   end
 end