Recognises an unstable or meaningful primary key
The key can change, be reused or be unknown when the row is created, or it carries meaning that can change. Every reference to the row breaks when it does.
Can AI do this?
AI does this well Most of the tested AI models master this. 10 of 10 models master it.
| Model | Tier | Probability of mastery | Status |
|---|---|---|---|
| gemini-4-argon | Flagship | 100% | Mastered |
| gemini-3.1-pro-preview | Flagship | 100% | Mastered |
| gpt-6-astra | Flagship | 100% | Mastered |
| claude-fable-5-1 | Flagship | 100% | Mastered |
| gemini-3.8-flash | Mid tier | 100% | Mastered |
| gpt-6.1-sol | Mid tier | 100% | Mastered |
| claude-sonnet-5-5 | Mid tier | 100% | Mastered |
| gemini-3.5-flash-lite | Low cost | 100% | Mastered |
| gpt-6-luna | Low cost | 100% | Mastered |
| claude-haiku-5-5 | Low cost | 100% | Mastered |
Mastered means a probability of at least 90% that the model has this knobit, estimated from its graded answers. “Not shown” means the answers do not settle it either way. How the models are tested.
What it looks like in practice
Expected result: The key and how it can change, be reused, be unknown or carry meaning
How it is assessed: Flags the deficient case and passes the acceptable one. Deficient: Account keyed on branch code plus sequence: a branch merger renumbers the branches and with them every key; Party keyed on name Acceptable: Account keyed on its IBAN, assigned once and never reused; Branch Identifier as a plain attribute; where no stable natural key exists, say so and record the matching rule (LOG-005, LOG-020, LOG-021, LOG-027)
Also known as: Unstable or meaningful key (logical model)
Related knobits
Builds on
Needed for
All 56 knobits of Derive the logical data model.
Source: Review checklist 05-logical, row 17; Codd 1970; Codd 1979; S&W ch. 6