#442

backend/app/controllers/posts_controller.rb

@@ -39,18 +39,16 @@ class PostsController < ApplicationController
 
     pt_max_sql =
         HistoryAccess.visible(PostVersion.all)
-        .select('post_id, MAX(created_at) AS max_updated_at')
-        .group('post_id')
+        .where('post_versions.post_id = posts.id')
+        .select('MAX(post_versions.created_at)')
         .to_sql
 
     updated_at_all_sql =
         'GREATEST(posts.updated_at,' +
-        'COALESCE(pt_max.max_updated_at, posts.updated_at))'
+        "COALESCE((#{ pt_max_sql }), posts.updated_at))"
 
     q =
         filtered_posts(locale)
-        .joins("LEFT JOIN (#{ pt_max_sql }) pt_max ON pt_max.post_id = posts.id")
-        .reselect('posts.*', Arel.sql("#{ updated_at_all_sql } AS updated_at_all"))
         .preload(:external_tags, :uploaded_user, :parents, :children,
                  post_tags: [:sections, { tag: [:deerjikists, :materials,
                                                 :tag_names, :tag_descriptions] }])
@@ -88,12 +86,15 @@ class PostsController < ApplicationController
              .limit(limit)
              .offset(offset)
              .to_a
+    latest_version_times = HistoryAccess.visible(PostVersion.where(post_id: posts.map(&:id)))
+        .group(:post_id).maximum(:created_at)
 
     q = q.except(:select, :order)
 
     render json: { posts: posts.map { |post|
       PostRepr.base(post, language_code: locale.language_code)
-              .merge(updated_at: post.updated_at_all).tap do |json|
+              .merge(updated_at: [post.updated_at, latest_version_times[post.id]].compact.max)
+              .tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)