/moderator/dashboard: optimize sql queries

* Converts queries to use active record instead of raw sql. This ensures
  that user objects are loaded by rails in the join, so that we
  don't have to issue `User.find` calls to load users one-by-one.

* Use `.includes` to preload associations used in the view, to avoid
  additional N+1 query problems (primarily, calls to link_to_user
  also causing users to be loaded one-by-one).

app/logical/moderator/dashboard/queries/artist.rb

@@ -1,28 +1,16 @@
 module Moderator
   module Dashboard
     module Queries
-      class Artist
-        attr_reader :user, :count
-
+      class Artist < ::Struct.new(:user, :count)
         def self.all(min_date, max_level)
-          sql = <<-EOS
-            SELECT artist_versions.updater_id AS updater_id, count(*)
-            FROM artist_versions
-            JOIN users ON users.id = artist_versions.updater_id
-            WHERE
-              artist_versions.created_at > ?
-              AND users.level <= ?
-            GROUP BY artist_versions.updater_id
-            ORDER BY count(*) DESC
-            LIMIT 10
-          EOS
-
-          ActiveRecord::Base.select_all_sql(sql, min_date, max_level).map {|x| new(x)}
-        end
-
-        def initialize(hash)
-          @user = ::User.find(hash["updater_id"])
-          @count = hash["count"]
+          ::ArtistVersion.joins(:updater)
+            .where("artist_versions.created_at > ?", min_date)
+            .where("users.level <= ?", max_level)
+            .group(:updater)
+            .order("count(*) desc")
+            .limit(10)
+            .count
+            .map { |user, count| new(user, count) }
         end
       end
     end

app/logical/moderator/dashboard/queries/comment.rb

@@ -1,31 +1,18 @@
 module Moderator
   module Dashboard
     module Queries
-      class Comment
-        attr_reader :comment, :count
-
+      class Comment < ::Struct.new(:comment, :count)
         def self.all(min_date, max_level)
-          sql = <<-EOS
-            SELECT comment_votes.comment_id, count(*)
-            FROM comment_votes
-            JOIN comments ON comments.id = comment_id
-            JOIN users ON users.id = comments.creator_id
-            WHERE
-              comment_votes.created_at > ?
-              AND comments.score < 0
-              AND users.level <= ?
-            GROUP BY comment_votes.comment_id
-            HAVING count(*) >= 3
-            ORDER BY count(*) DESC
-            LIMIT 10
-          EOS
-
-          ActiveRecord::Base.select_all_sql(sql, min_date, max_level).map {|x| new(x)}
-        end
-
-        def initialize(hash)
-          @comment = ::Comment.find(hash["comment_id"])
-          @count = hash["count"]
+          ::CommentVote.joins(comment: [:creator])
+            .where("comments.score < 0")
+            .where("comment_votes.created_at > ?", min_date)
+            .where("users.level <= ?", max_level)
+            .group(:comment)
+            .having("count(*) >= 3")
+            .order("count(*) desc")
+            .limit(10)
+            .count
+            .map { |comment, count| new(comment, count) }
         end
       end
     end

app/logical/moderator/dashboard/queries/mod_action.rb

@@ -3,7 +3,7 @@ module Moderator
     module Queries
       class ModAction
         def self.all
-          ::ModAction.order("id desc").limit(10)
+          ::ModAction.includes(:creator).order("id desc").limit(10)
         end
       end
     end

app/logical/moderator/dashboard/queries/note.rb

@@ -1,28 +1,16 @@
 module Moderator
   module Dashboard
     module Queries
-      class Note
-        attr_reader :user, :count
-
+      class Note < ::Struct.new(:user, :count)
         def self.all(min_date, max_level)
-          sql = <<-EOS
-            SELECT note_versions.updater_id, count(*)
-            FROM note_versions
-            JOIN users ON users.id = note_versions.updater_id
-            WHERE
-              note_versions.created_at > ?
-              AND users.level <= ?
-            GROUP BY note_versions.updater_id
-            ORDER BY count(*) DESC
-            LIMIT 10
-          EOS
-
-          ActiveRecord::Base.select_all_sql(sql, min_date, max_level).map {|x| new(x)}
-        end
-
-        def initialize(hash)
-          @user = ::User.find(hash["updater_id"])
-          @count = hash["count"]
+          ::NoteVersion.joins(:updater)
+            .where("note_versions.created_at > ?", min_date)
+            .where("users.level <= ?", max_level)
+            .group(:updater)
+            .order("count(*) desc")
+            .limit(10)
+            .count
+            .map { |user, count| new(user, count) }
         end
       end
     end

app/logical/moderator/dashboard/queries/post_appeal.rb

@@ -2,28 +2,13 @@ module Moderator
   module Dashboard
     module Queries
       class PostAppeal
-        attr_reader :post, :count
-
         def self.all(min_date)
-          sql = <<-EOS
-            SELECT post_appeals.post_id, count(*)
-            FROM post_appeals
-            JOIN posts ON posts.id = post_appeals.post_id
-            WHERE
-              post_appeals.created_at > ?
-              and posts.is_deleted = true
-              and posts.is_pending = false
-            GROUP BY post_appeals.post_id
-            ORDER BY count(*) DESC
-            LIMIT 10
-          EOS
-
-          ActiveRecord::Base.select_all_sql(sql, min_date).map {|x| new(x)}
-        end
-
-        def initialize(hash)
-          @post = ::Post.find(hash["post_id"])
-          @count = hash["count"]
+          ::Post.joins(:appeals).includes(:uploader, :flags, appeals: [:creator])
+            .deleted
+            .where("post_appeals.created_at > ?", min_date)
+            .group(:id)
+            .order("count(*) desc")
+            .limit(10)
         end
       end
     end

app/logical/moderator/dashboard/queries/tag.rb

@@ -1,9 +1,7 @@
 module Moderator
   module Dashboard
     module Queries
-      class Tag
-        attr_reader :user, :count
-
+      class Tag < ::Struct.new(:user, :count)
         def self.all(min_date, max_level)
           return [] unless PostArchive.enabled?
 
@@ -13,10 +11,6 @@ module Moderator
 
           records.select { |rec| rec.user.level <= max_level }.sort_by(&:count).reverse.take(10)
         end
-
-        def initialize(user, count)
-          @user, @count = user, count
-        end
       end
     end
   end

app/logical/moderator/dashboard/queries/upload.rb

@@ -1,28 +1,16 @@
 module Moderator
   module Dashboard
     module Queries
-      class Upload
-        attr_reader :user, :count
-
+      class Upload < ::Struct.new(:user, :count)
         def self.all(min_date, max_level)
-          sql = <<-EOS
-            select uploader_id, count(*)
-            from posts
-            join users on uploader_id = users.id
-            where
-              posts.created_at > ?
-              and level <= ?
-            group by posts.uploader_id
-            order by count(*) desc
-            limit 10
-          EOS
-
-          ActiveRecord::Base.select_all_sql(sql, min_date, max_level).map {|x| new(x)}
-        end
-
-        def initialize(hash)
-          @user = ::User.find(hash["uploader_id"])
-          @count = hash["count"]
+          ::Post.joins(:uploader)
+            .where("posts.created_at > ?", min_date)
+            .where("users.level <= ?", max_level)
+            .group(:uploader)
+            .order("count(*) desc")
+            .limit(10)
+            .count
+            .map { |user, count| new(user, count) }
         end
       end
     end

app/logical/moderator/dashboard/queries/user_feedback.rb

@@ -3,7 +3,7 @@ module Moderator
     module Queries
       class UserFeedback
         def self.all
-          ::UserFeedback.order("id desc").limit(10)
+          ::UserFeedback.includes(:user).order("id desc").limit(10)
         end
       end
     end

app/logical/moderator/dashboard/queries/wiki_page.rb

@@ -1,28 +1,16 @@
 module Moderator
   module Dashboard
     module Queries
-      class WikiPage
-        attr_reader :user, :count
-
+      class WikiPage < ::Struct.new(:user, :count)
         def self.all(min_date, max_level)
-          sql = <<-EOS
-            SELECT wiki_page_versions.updater_id, count(*)
-            FROM wiki_page_versions
-            JOIN users ON users.id = wiki_page_versions.updater_id
-            WHERE
-              wiki_page_versions.created_at > ?
-              AND users.level <= ?
-            GROUP BY wiki_page_versions.updater_id
-            ORDER BY count(*) DESC
-            LIMIT 10
-          EOS
-
-          ActiveRecord::Base.select_all_sql(sql, min_date, max_level).map {|x| new(x)}
-        end
-
-        def initialize(hash)
-          @user = ::User.find(hash["updater_id"])
-          @count = hash["count"]
+          ::WikiPageVersion.joins(:updater)
+            .where("wiki_page_versions.created_at > ?", min_date)
+            .where("users.level <= ?", max_level)
+            .group(:updater)
+            .order("count(*) desc")
+            .limit(10)
+            .count
+            .map { |user, count| new(user, count) }
         end
       end
     end

app/views/moderator/dashboards/_activity_appeal.html.erb

@@ -10,13 +10,13 @@
     </tr>
   </thead>
   <tbody>
-    <% @dashboard.appeals.each do |appeal| %>
+    <% @dashboard.appeals.each do |post| %>
       <tr>
-        <td><%= link_to image_tag(appeal.post.preview_file_url), post_path(appeal.post) %></td>
-        <td><%= mod_link_to_user appeal.post.uploader, :negative %></td>
-        <td><%= post_flag_reasons(appeal.post) %></td>
-        <td><%= post_appeal_reasons(appeal.post) %></td>
-        <td><%= appeal.post.score %></td>
+        <td><%= link_to image_tag(post.preview_file_url), post_path(post) %></td>
+        <td><%= mod_link_to_user post.uploader, :negative %></td>
+        <td><%= post_flag_reasons(post) %></td>
+        <td><%= post_appeal_reasons(post) %></td>
+        <td><%= post.score %></td>
       </tr>
     <% end %>
   </tbody>