Indexing foreign keys and scalars

[ghost]

• Is there a specific reason as to why the foreign key to User in Token is indexed, while the ones in followers table aren't?
• On this line, is there an advantage of doing db.session.scalars(User.select().where(User.id == self.id, User.following.contains(user))).one_or_none() is not None over something like db.session.scalar(User.select().where(User.id == self.id, User.following.contains(user))) is not None?

Thanks!

[miguelgrinberg]

• The foreign keys in the followers table are primary keys, so they are always indexed.
• The one_or_none() method will raise an exception if two or more results are found matching the condition. The scalar() would not.

[ghost]

• Is there any scenario where it'll return more than one result? We're already filtering by User's primary key.

[miguelgrinberg]

With the current schema it would never return more than one result.