From 1343d40558cd1aeeb33599a41dd2a46743849443 Mon Sep 17 00:00:00 2001
From: Sam <sam.saffron@gmail.com>
Date: Thu, 18 Jun 2015 09:58:32 +1000
Subject: [PATCH] PERF: deleting a post in huge topics was timing out

- add missing index to user actions for fast retrieval by post
- add missing indexes to users for fast retrieval of staff
- only refresh topic_users liked/bookmarked cache for affected users
---
 app/models/topic_user.rb                                  | 8 ++++++++
 ...0617233018_add_index_target_post_id_on_user_actions.rb | 5 +++++
 db/migrate/20150617234511_add_staff_index_to_users.rb     | 6 ++++++
 lib/post_destroyer.rb                                     | 2 +-
 4 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 db/migrate/20150617233018_add_index_target_post_id_on_user_actions.rb
 create mode 100644 db/migrate/20150617234511_add_staff_index_to_users.rb

diff --git a/app/models/topic_user.rb b/app/models/topic_user.rb
index 2611039f311..30fdf0be304 100644
--- a/app/models/topic_user.rb
+++ b/app/models/topic_user.rb
@@ -232,6 +232,7 @@ class TopicUser < ActiveRecord::Base
 
   def self.update_post_action_cache(opts={})
     user_id = opts[:user_id]
+    post_id = opts[:post_id]
     topic_id = opts[:topic_id]
     action_type = opts[:post_action_type]
 
@@ -277,6 +278,13 @@ SQL
       builder.where("tu2.topic_id = :topic_id", topic_id: topic_id)
     end
 
+    if post_id
+      builder.where("tu2.topic_id IN (SELECT topic_id FROM posts WHERE id = :post_id)", post_id: post_id)
+      builder.where("tu2.user_id IN (SELECT user_id FROM post_actions
+                                     WHERE post_id = :post_id AND
+                                           post_action_type_id = :action_type_id)")
+    end
+
     builder.exec(action_type_id: PostActionType.types[action_type])
   end
 
diff --git a/db/migrate/20150617233018_add_index_target_post_id_on_user_actions.rb b/db/migrate/20150617233018_add_index_target_post_id_on_user_actions.rb
new file mode 100644
index 00000000000..973bda76f04
--- /dev/null
+++ b/db/migrate/20150617233018_add_index_target_post_id_on_user_actions.rb
@@ -0,0 +1,5 @@
+class AddIndexTargetPostIdOnUserActions < ActiveRecord::Migration
+  def change
+    add_index :user_actions, [:target_post_id]
+  end
+end
diff --git a/db/migrate/20150617234511_add_staff_index_to_users.rb b/db/migrate/20150617234511_add_staff_index_to_users.rb
new file mode 100644
index 00000000000..f060b9b1693
--- /dev/null
+++ b/db/migrate/20150617234511_add_staff_index_to_users.rb
@@ -0,0 +1,6 @@
+class AddStaffIndexToUsers < ActiveRecord::Migration
+  def change
+    add_index :users, [:id], name: 'idx_users_admin', where: 'admin'
+    add_index :users, [:id], name: 'idx_users_moderator', where: 'moderator'
+  end
+end
diff --git a/lib/post_destroyer.rb b/lib/post_destroyer.rb
index fb6bd9079c9..818f3766356 100644
--- a/lib/post_destroyer.rb
+++ b/lib/post_destroyer.rb
@@ -90,7 +90,7 @@ class PostDestroyer
       end
       update_associated_category_latest_topic
       update_user_counts
-      TopicUser.update_post_action_cache(topic_id: @post.topic_id)
+      TopicUser.update_post_action_cache(post_id: @post.id)
     end
 
     feature_users_in_the_topic if @post.topic