Comment 4 for bug 687752

Moving the hash from LFC to LFA is duplicating the hash - there can be multiple LFAs linked to an LFC. It will complicate garbage collection logic, and the data model is broken (well... denormalized) in that you could have multiple LFAs with differing hashes pointing to an LFC.

I'm not sure how your intended work flow plays with other users of the Librarian. If a file is uploaded into the Librarian from some other part of Launchpad, will the publisher refuse to publish it? The alternative of having a table of hashes that Soyuz will block uploads for seems simpler for everyone.