I can not get https://quarry.wmflabs.org/query/27897 to work, which is trying to find files uploaded without corresponding description page. I run into some new uploads like that (File:Muzeum Walki i Męczeństwa w Treblince 2018e.jpg) and would like to see if there are more.
Topic on Talk:Quarry
Append page_namespace = 6 to it. This will make your query use the unique index and will be a lot faster.