// Build read models and projections from event streams. Use when implementing CQRS read sides, building materialized views, or optimizing query performance in event-sourced systems.
| name | projection-patterns |
| description | Build read models and projections from event streams. Use when implementing CQRS read sides, building materialized views, or optimizing query performance in event-sourced systems. |
Comprehensive guide to building projections and read models for event-sourced systems.
┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│ Event Store │────►│ Projector │────►│ Read Model │
│ │ │ │ │ (Database) │
│ ┌─────────┐ │ │ ┌─────────┐ │ │ ┌─────────┐ │
│ │ Events │ │ │ │ Handler │ │ │ │ Tables │ │
│ └─────────┘ │ │ │ Logic │ │ │ │ Views │ │
│ │ │ └─────────┘ │ │ │ Cache │ │
└─────────────┘ └─────────────┘ └─────────────┘
| Type | Description | Use Case |
|---|---|---|
| Live | Real-time from subscription | Current state queries |
| Catchup | Process historical events | Rebuilding read models |
| Persistent | Stores checkpoint | Resume after restart |
| Inline | Same transaction as write | Strong consistency |
Full template library and detailed worked examples live in references/details.md. Read that file when you need the concrete templates.
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