add index on post_versions.updated_at

app/views/user_feedbacks/index.html.erb

@@ -18,7 +18,7 @@
             <td><%= feedback.category %></td>
             <td><%= link_to feedback.user_name, user_path(feedback.user_id) %></td>
             <td><%= link_to feedback.creator_name, user_path(feedback.creator_id) %></td>
-            <td><%= time_ago_in_words_tagged(feedback.created_at) %></td>
+            <td><%= compact_time(feedback.created_at) %></td>
             <td><%= format_text(feedback.body) %></td>
           </tr>
         <% end %>

db/migrate/20130221032344_add_index_updated_at_on_post_versions.rb

@@ -0,0 +1,9 @@
+class AddIndexUpdatedAtOnPostVersions < ActiveRecord::Migration
+  def up
+    add_index :post_versions, :updated_at
+  end
+
+  def down
+    remove_index :post_versions, :updated_at
+  end
+end