PERF: last seen index on users

app/models/badge.rb

@@ -250,6 +250,7 @@ end
 #  badge_grouping_id :integer          default(5), not null
 #  trigger           :integer
 #  show_posts        :boolean          default(FALSE), not null
+#  system            :boolean          default(FALSE), not null
 #
 # Indexes
 #

app/models/user.rb

@@ -784,6 +784,7 @@ end
 #
 #  index_users_on_auth_token      (auth_token)
 #  index_users_on_last_posted_at  (last_posted_at)
+#  index_users_on_last_seen_at    (last_seen_at)
 #  index_users_on_username        (username) UNIQUE
 #  index_users_on_username_lower  (username_lower) UNIQUE
 #

app/models/user_profile.rb

@@ -95,4 +95,9 @@ end
 #  bio_cooked           :text
 #  dismissed_banner_key :integer
 #  profile_background   :string(255)
+#  bio_cooked_version   :integer
+#
+# Indexes
+#
+#  index_user_profiles_on_bio_cooked_version  (bio_cooked_version)
 #

db/migrate/20140807033123_add_index_on_last_seen_to_users.rb

@@ -0,0 +1,5 @@
+class AddIndexOnLastSeenToUsers < ActiveRecord::Migration
+  def change
+    add_index :users, [:last_seen_at]
+  end
+end