[Dbix-class] Finding missing rows -- JOIN with multiple conditions

[xli]

>much faster) with just a join.   But I need to have extra join condition
>(in *bold* below).


Is this what you're after?

http://search.cpan.org/dist/DBIx-Class/lib/DBIx/Class/Relationship/Base.pm#condition

   "will result in the JOIN clause:

     ... FROM book me
         LEFT JOIN edition editions ON
              editions.publisher_id = me.publisher_id
          AND editions.type_id = me.type_id ...
    "