[sqlalchemy] Polymorphic inheritance with dynamically created tables: issues with undefined polymorphic identity

I have a base Dataset class that I'd like to dynamically inherit from. When a user uploads a new dataset, I create a new table as shown below, and populate it with data. My two most common use-cases: 1. Retrieving entire dataset. I want to return dataset_x where x is an integer that

[sqlalchemy] Help with a custom "seconds_interval()" construct

I'm interested in being able to use second time intervals on PostgreSQL, Oracle 8 *and *modern Oracle versions, agnostically. The native python timedelta works great for the postgres and cx_Oracle drivers. However *cx_Oracle connected to Oracle 8 won't support this* so I'm building my own