Data structures and meaning
Key-value structure and lookup contract
A key-value space: key shapes, value payloads, and the lookup contract between them.
ddn@1New DDN source
Why use it?
Make key design a reviewed decision — it decides distribution, collisions and every access pattern.
When it helps
Designing caches, key-value stores, or any lookup-first data structure.
How to read it
- Keys are the contract; values are opaque to readers of the key space.
- Lookup paths start at the key, never the value.
What you need
- Key shapes and their parts
- Payload sketches
- Read patterns
Things to check
- Do not design keys you cannot construct from what the reader already knows.
- Do not hide a second lookup path the contract does not mention.
Scope of this diagram
Contract documentation; no cache behaviour is simulated.
Work with the converted example
- Open the viewer and select
diagram. Inspect the rendered view and its source. - Open the designer. Keep the selected profile and inspect its legal palette and property controls.
- Change one displayed title or an appropriate data value. Apply the edit and check the resulting diagram.
- Run the verifier and review its diagnostics before moving complete content into review.
- Download your edited DDN source to retain the change.
The example uses the indentation-based ddn-next-1 dialect. The language guide explains reusable definitions, dotted data rows and explicit property blocks.