A library of files: a row a file, owned by someone (an account, a site), referenced from many records, kept when the record that first used it is deleted. Its tables are Storehouse.Ecto.Migrations's; which records use each file is Storehouse.Ecto.Usage's.

For a file a record has alone (an avatar, an invoice), a column of the record is simpler: Storehouse.Ecto.File, with no table.

This module is a schema of storehouse_blobs. An app with a table of its own, or fields of its own (a description, a credit), writes its schema with the same fields:

defmodule MyApp.Photo do
  use Storehouse.Ecto.Blob.Schema, usages: "photo_usages"

  schema "photos" do
    Storehouse.Ecto.Blob.Schema.fields()
    field :alt_text, :string
  end
end

and gives it as schema: to this module's functions and Storehouse.Ecto.Usage's. Its migration is Storehouse.Ecto.Migrations.up(blobs: "photos", usages: "photo_usages"), then its own columns.

A file into the library

{:ok, file} = Storehouse.store(upload.path, owner: "sites/7")
{:ok, blob} = Storehouse.Ecto.Blob.insert(Repo, file, owner: "sites/7")

The same file again, for the same owner, is the row the library has: {:existing, blob}, by the checksum.