# Event Store Design

> Design and implement event stores for event-sourced systems. Use when building event sourcing infrastructure, choosing event store technologies, or implementing event persistence patterns.

Source: https://skillsagentes.com/skills/wshobson/agents/event-store-design
Repository: https://github.com/wshobson/agents
Author: wshobson
License: MIT
Updated: hace 2 meses
Context cost: 47 tok installed, 1k tok once triggered, 3.9k tok with every bundled file
Bundle: 2 files, 15 KB
Permissions requested: none declared

## Install

```bash
npx -y skills add wshobson/agents --skill event-store-design --agent claude-code
```

## What it does

- Guía el diseño de arquitecturas de event store para sistemas basados en event sourcing
- Compara tecnologías como EventStoreDB, PostgreSQL, Kafka, DynamoDB y Marten
- Define requisitos clave: append-only, ordenación, versionado, suscripciones e idempotencia
- Aporta buenas prácticas sobre stream IDs, correlation/causation IDs y evolución de esquemas

## Use it when

- Al diseñar infraestructura de event sourcing
- Al elegir entre distintas tecnologías de event store
- Al implementar un event store propio
- Al optimizar el almacenamiento y la recuperación de eventos, o planificar su escalado

## What triggers it

- "Ayúdame a diseñar el esquema de un event store para mi sistema"
- "¿Qué tecnología de event store me conviene, EventStoreDB o PostgreSQL?"
- "Necesito implementar concurrencia optimista en mi event store"

## Before you install

- Para plantillas y ejemplos detallados, consultar el archivo references/details.md.

## Files

- SKILL.md — 4 KB
- references/details.md — 11 KB

## SKILL.md

Reproduced verbatim from wshobson/agents under MIT. This section is the upstream document and is in English.

# 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

| Requirement       | Description                        |
| ----------------- | ---------------------------------- |
| **Append-only**   | Events are immutable, only appends |
| **Ordered**       | Per-stream and global ordering     |
| **Versioned**     | Optimistic concurrency control     |
| **Subscriptions** | Real-time event notifications      |
| **Idempotent**    | Handle duplicate writes safely     |

## Technology Comparison

| Technology       | Best For                  | Limitations                      |
| ---------------- | ------------------------- | -------------------------------- |
| **EventStoreDB** | Pure event sourcing       | Single-purpose                   |
| **PostgreSQL**   | Existing Postgres stack   | Manual implementation            |
| **Kafka**        | High-throughput streaming | Not ideal for per-stream queries |
| **DynamoDB**     | Serverless, AWS-native    | Query limitations                |
| **Marten**       | .NET ecosystems           | .NET specific                    |

## 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

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Skills Agentes — https://skillsagentes.com/skills/wshobson/agents/event-store-design