Realtime Collaborative Editor

Summary

An architecture for multi-user document editing where users see each other's changes in near real-time. PostgreSQL provides durable state persistence, Redis coordinates ephemeral session state and pub/sub for live change propagation, and connection pooling protects the database from WebSocket-induced connection churn.

Problem Statement

Collaborative editing requires changes from one user to be propagated to all other users editing the same document within milliseconds. Persistent WebSocket connections create high connection counts that overwhelm standard database connection limits. Ephemeral presence data (cursor positions, active users) must not be stored in the primary database. The system must handle concurrent conflicting edits gracefully.