#442

backend/app/controllers/posts_controller.rb

@@ -37,7 +37,7 @@ class PostsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    updated_at_all_sql = 'posts.updated_at'
+    needs_history_join = order[0] == 'updated_at' || updated_between.any?(&:present?)
 
     q =
         filtered_posts(locale)
@@ -56,12 +56,25 @@ class PostsController < ApplicationController
     end
     q = q.where('posts.created_at >= ?', created_between[0]) if created_between[0]
     q = q.where('posts.created_at <= ?', created_between[1]) if created_between[1]
+    count_scope = q
+    if needs_history_join
+      history_times = HistoryAccess.visible(PostVersion.all)
+          .select('post_id, MAX(created_at) AS latest_at').group(:post_id)
+      q = q.joins("LEFT JOIN (#{ history_times.to_sql }) history_times " +
+                  'ON history_times.post_id = posts.id')
+      updated_at_all_sql = 'GREATEST(posts.updated_at, ' +
+          'COALESCE(history_times.latest_at, posts.updated_at))'
+    end
     if updated_between[0]
       q = q.where("#{ updated_at_all_sql } >= ?", updated_between[0])
     end
     if updated_between[1]
       q = q.where("#{ updated_at_all_sql } <= ?", updated_between[1])
     end
+    count_scope = q if updated_between.any?(&:present?)
+    if needs_history_join
+      q = q.select('posts.*', "#{ updated_at_all_sql } AS updated_at")
+    end
 
     sort_sql =
         case order[0]
@@ -78,14 +91,20 @@ 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)
+    latest_version_times =
+        if needs_history_join
+          { }
+        else
+          HistoryAccess.visible(PostVersion.where(post_id: posts.map(&:id)))
+              .group(:post_id).maximum(:created_at)
+        end
 
-    q = q.except(:select, :order)
+    count_scope = count_scope.except(:select, :order)
 
     render json: { posts: posts.map { |post|
+      updated_at = [post.updated_at, latest_version_times[post.id]].compact.max
       PostRepr.base(post, language_code: locale.language_code)
-              .merge(updated_at: post.updated_at).tap do |json|
+          .merge('updated_at' => updated_at).tap do |json|
         json['thumbnail'] =
             if post.thumbnail.attached?
               rails_storage_proxy_url(post.thumbnail, only_path: false)
@@ -93,7 +112,7 @@ class PostsController < ApplicationController
               nil
             end
       end
-    }, count: q.group_values.present? ? q.count.size : q.count }
+    }, count: count_scope.group_values.present? ? count_scope.count.size : count_scope.count }
   end
 
   def random