Why store ecto_arc field in database?

I think you misunderstood me. I meant if the file I am uploading will be renamed in def filename and this new file name is only dependent on scope.id. In that can do I need to store it in database at all? I mean id is not going to change whatsoever.

URL example on arc readme file. The url generated is not dependent on filename “selfie.png” at all, so why it needs to be there?

Avatar.url({"selfie.png", user}) #=> "https://bucket.s3.amazonaws.com/uploads/1/original.png"