add created_at to the page_views index on account_id

Change-Id: I2a23a1f5416eae7523260b963fa80b64c30b07b2
Reviewed-on: https://gerrit.instructure.com/2729
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>

db/migrate/20110321204131_add_created_at_to_page_views_index.rb

@@ -0,0 +1,11 @@
+class AddCreatedAtToPageViewsIndex < ActiveRecord::Migration
+  def self.up
+    remove_index :page_views, :column => :account_id
+    add_index :page_views, [ :account_id, :created_at ]
+  end
+
+  def self.down
+    remove_index :page_views, :column => [ :account_id, :created_at ]
+    add_index :page_views, :account_id
+  end
+end