a month ago
Not exactly a constraint of the database structure, but rather a design decision. For each attachment, there is a record in a table that contains the unique reference Id and a path to the file. The file path field could hold anything they wanted as long as the file name would have been unique (by appending the unique reference Id for example to the filename).
It is an odd design choice, one that I would have not made, but we have to live with it.