Part 3 - Derived data

No application uses a single datastore. It's often a combination of several:

* Databases
* (Search) Indexes
* Caches
* Datawarehouses

• System of record
  • It's the source of truth!
• Derived data systems
  • Takes data from another system and transforms it
  • If derived data is lost, you can get it again from the source
  • Typical example: Cache!