Single-Table Inventory Demo
A tiny operations-style inventory system that updates machine and SKU counts, writes adjustment events, and shows why DynamoDB access patterns matter.
ID
API
L
DDB
AWS
Problem
Inventory systems look simple until the business needs current stock, machine-level history, restock events, and auditability. This demo keeps the scope small while showing the data-model thought process.
Design
- Cognito and API Gateway protect the API.
- Lambda validates a machine, SKU, and stock delta.
- DynamoDB stores the current machine/SKU quantity and a separate event item under the same user partition.
- The browser receives the updated item plus a compact inventory list.
Access pattern
The live query is intentionally narrow: list the signed-in reviewer's current machine/SKU records. Event history is written with a separate sort-key prefix so the table can later support restock audit queries without changing storage engines.
Cost controls
Reviewer actions are limited to three per day, deltas are capped between -25 and 25, records expire with TTL, and the implementation reuses the existing provisioned DynamoDB table.