Event Sourcing

• Similar to Redux but persisted and synced across devices
• Core idea: Separate read vs write model
  • Read model: App database (i.e. SQLite)
  • Write model: Ordered log of all mutation events
• Related topics
  • Domain driven design
• Benefits
  • Simple mental model
  • Scalable
  • Flexible
    • You can easily evolve the read model based on your query patterns as your app requirements change over time
    • Automatic migrations of the read model (i.e. app database)
    • Write model can also be evolved (e.g. via versioned mutations and optionally mapping old mutations to new ones)
  • History of all state changes is captured (e.g. for auditing and debugging)
    • Foundation for syncing
• Downsides
  • Slightly more boilerplate to manually define mutations
  • Need to be careful so mutation log doesn’t grow too much