Recognises rolled-down subtypes losing supertype constraints
One table per subtype and none for the supertype. Uniqueness across subtypes cannot be declared, nothing stops one instance appearing in two subtype tables, and a relationship to the supertype has no single table to reference, so it becomes a polymorphic association (logical row 22).
Can AI do this?
Not tested yet
No AI benchmark covers this knobit yet. New results are announced in the Can AI Do the Job? newsletter.
What it looks like in practice
Expected result: The lost cross-subtype uniqueness and supertype reference
How it is assessed: Flags the deficient case and passes the acceptable one. Deficient: person and organisation, no party; account_holder.party_id cannot have a foreign key; nothing stops one id being used in both tables Acceptable: A party table with the shared key; person and organisation keyed by party_id with an FK to it; exclusivity enforced by carrying the discriminator into each subtype's key, or by a DQ rule
Also known as: Subtypes rolled down, supertype constraints lost (physical model)
Related knobits
Builds on
- K-519 Recognises undeclared subtype constraints
- K-652 Explains the implementation options for subtypes
All 40 knobits of Design the physical data model.
Source: Review checklist 06-physical, row 7; E&N 9.2; S&W 11.3