adjust qurey to include messages, once everything is read

then mark first_topic_unread_at to be current time

app/models/user_stat.rb

@@ -85,7 +85,7 @@ class UserStat < ActiveRecord::Base
 
     exec_sql <<SQL
     UPDATE user_stats us
-    SET first_topic_unread_at = COALESCE(X.first_unread_at, 'epoch')
+    SET first_topic_unread_at = COALESCE(X.first_unread_at, current_timestamp)
     FROM
     (
       SELECT u.id user_id, MIN(last_unread_at) first_unread_at
@@ -96,7 +96,7 @@ class UserStat < ActiveRecord::Base
                                                                 THEN t.highest_staff_post_number
                                                                 ELSE t.highest_post_number
                                                                END
-        AND t.deleted_at IS NULL AND t.archetype <> 'private_message'
+        AND t.deleted_at IS NULL
       GROUP BY u.id
     ) X
     WHERE X.user_id = us.user_id AND X.first_unread_at <> first_topic_unread_at

db/migrate/20170524182846_add_unread_tracking_columns.rb

@@ -20,8 +20,8 @@ SQL
                                                                 THEN topics.highest_staff_post_number
                                                                 ELSE topics.highest_post_number
                                                                END
-        AND topics.deleted_at IS NULL AND topics.archetype <> 'private_message'
+        AND topics.deleted_at IS NULL
-    ), 'epoch')
+    ), current_timestamp)
 SQL
 
     add_index :topics, [:last_unread_at]