Requirements

Functional Requirements:

• Create a short URL for a given long URL.
• Return the long URL associated with a given short URL.

Non-Functional Requirements:

• Low latency on _read_ path (adding new urls MUST NOT slowdown lookup)
• Write path is less frequent, so write performance is secondary

API Design

POST /alias {"url": string}

Returns {"url": string, "slug": string}

GET /alias/{slug}

Returns {"url": string}

High-Level Design

Clients calls API server.

API server looks up slug in database

Lookup is based on indexed field, so that btree can be used.

Detailed Component Design

Server: thin microservice, maintains connection pool to database

Database: read replicas, single write primary for write path