Real-Time Event Sourcing with Async Database Patterns

Implement an event sourcing system using async Python (asyncio) with PostgreSQL for a real-time collaboration platform. Design a robust event log that supports transactional integrity, versioning, and replay capabilities. Create a custom event store that can handle concurrent writes, implement optimistic concurrency control, and provide efficient event reconstruction. Include mechanisms for snapshoting, event compression, and zero-downtime schema migrations.