Question

Is the following kosher?

schema.rb
  users
    id:int (autoincr.)
    uid:string <----------------
    ...

  fb_friends
    id:int (autoincr.)
    uid:int <-------------------
    friend_uid:int
    ...

user.rb
   has_many :fb_friends, :primary_key => "uid", :foreign_key => "uid"

Note that the keys that tie a “user” and their “fb_friends” together are of different data types (string and int). In an ideal world, I probably wouldn’t do this, but given the current system architecture, this seems to be the solution that would work best.

But is this okay to do / will it work without snafoos?

Answer 1

It depends on the DB engine you’re using, e.g, for mysql =>

Corresponding columns in the foreign
key and the referenced key must have
similar internal data types inside
InnoDB so that they can be compared
without a type conversion. The size
and sign of integer types must be the
same. The length of string types need
not be the same. For nonbinary
(character) string columns, the
character set and collation must be
the same.

More info here, Anyways, I won’t say it’s a good practice to compare fields of different types :(.

Hope it helps you!