API の処理に時間がかかりすぎる問題 (#442) (#449)

Reviewed-on: #449
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/app/controllers/post_versions_controller.rb

@@ -14,8 +14,9 @@ class PostVersionsController < ApplicationController
 
     offset = (page - 1) * limit
 
-    q = HistoryAccess.visible(version_scope)
+    q = HistoryAccess.visible(PostVersion.all)
     q = q.where('post_versions.post_id = ?', post_id) if post_id
+    q = q.with_previous_version if tag_id || external_tag_id
     if external_tag_id || (tag_id && !(Tag.exists?(id: tag_id)))
       q = q.where('JSON_CONTAINS(post_versions.tags_json,' +
                   "JSON_OBJECT('external_tag_id', #{ external_tag_id || tag_id })) " +
@@ -28,9 +29,12 @@ class PostVersionsController < ApplicationController
 
     count = q.except(:select, :order, :limit, :offset).count
 
-    versions = q.order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
+    ids = q.order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
                 .limit(limit)
                 .offset(offset)
+                .pluck('post_versions.id')
+    versions = version_scope.merge(q).where(id: ids)
+        .order(Arel.sql('post_versions.created_at DESC, post_versions.id DESC'))
 
     render json: { versions: serialise_versions(versions, locale.language_code), count:, population_count: HistoryAccess.population_count(PostVersion) }
   end