Event Store Design

Event Store Design

Comprehensive guide to designing event stores for event-sourced applications.

When to Use This Skill

• Designing event sourcing infrastructure
• Choosing between event store technologies
• Implementing custom event stores
• Optimizing event storage and retrieval
• Setting up event store schemas
• Planning for event store scaling

Core Concepts

1. Event Store Architecture

┌─────────────────────────────────────────────────────┐│                    Event Store                       │├─────────────────────────────────────────────────────┤│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐ ││  │   Stream 1   │  │   Stream 2   │  │   Stream 3   │ ││  │ (Aggregate)  │  │ (Aggregate)  │  │ (Aggregate)  │ ││  ├─────────────┤  ├─────────────┤  ├─────────────┤ ││  │ Event 1     │  │ Event 1     │  │ Event 1     │ ││  │ Event 2     │  │ Event 2     │  │ Event 2     │ ││  │ Event 3     │  │ ...         │  │ Event 3     │ ││  │ ...         │  │             │  │ Event 4     │ ││  └─────────────┘  └─────────────┘  └─────────────┘ │├─────────────────────────────────────────────────────┤│  Global Position: 1 → 2 → 3 → 4 → 5 → 6 → ...     │└─────────────────────────────────────────────────────┘

2. Event Store Requirements

Technology Comparison

Templates and detailed worked examples

Full template library and detailed worked examples live in references/details.md. Read that file when you need the concrete templates.

Best Practices

Do's

• Use stream IDs that include aggregate type - Order-{uuid}
• Include correlation/causation IDs - For tracing
• Version events from day one - Plan for schema evolution
• Implement idempotency - Use event IDs for deduplication
• Index appropriately - For your query patterns

Don'ts

• Don't update or delete events - They're immutable facts
• Don't store large payloads - Keep events small
• Don't skip optimistic concurrency - Prevents data corruption
• Don't ignore backpressure - Handle slow consumers