SQLAlchemy normally presents a many-to-many relationship as a list on
both sides. You've got "Machine.children", which is a list of Options,
and "Option.parents", which is a list of Machines.
If you remove one of the options from a machine.children list, you'll
find that SQLAlchemy removes the
This is the same problem: you're writing a query that joins 3 tables
together, and then applying a "LIMIT 20" to that query. If you look
carefully at your 20 rows of psql output, I expect you'll see the same
aggregates_id appear more than once. There are less than 20 distinct
Aggregate objects.
