Improve performance of account_media_status_ids (#6729)

app/controllers/api/v1/accounts/statuses_controller.rb

@@ -51,7 +51,13 @@ def only_media_scope
   end
 
   def account_media_status_ids
-    @account.media_attachments.attached.reorder(nil).select(:status_id).distinct
+    # `SELECT DISTINCT id, updated_at` is too slow, so pluck ids at first, and then select id, updated_at with ids.
+    # Also, Avoid getting slow by not narrowing down by `statuses.account_id`.
+    # When narrowing down by `statuses.account_id`, `index_statuses_20180106` will be used
+    # and the table will be joined by `Merge Semi Join`, so the query will be slow.
+    Status.joins(:media_attachments).merge(@account.media_attachments).permitted_for(@account, current_account)
+          .paginate_by_max_id(limit_param(DEFAULT_STATUSES_LIMIT), params[:max_id], params[:since_id])
+          .reorder(id: :desc).distinct(:id).pluck(:id)
   end
 
   def pinned_scope