A 1:M (one to many) non-identifying means that the associated record in the -one- table is not a parent of the associated record in the -many- table, but rather just related. An example: an identifying 1:M would be a building which has many rooms. The -one- table carries data about the building .. e.g.,...

If you have a 2.7 GB file, file_exists(’./filename’) works but is_file( ‘./filename’ ); fails gracefully. Not even Apache handles these kind of files very well so take care.