The Runtime Theory
Software ArchitectureIn production

CQRS Explained

Recording in progress
#cqrs#architecture#event-sourcing#patterns

Most systems read and write one model — and that single model ends up bad at both jobs. CQRS splits them: commands mutate the write model, queries read a separate read model, and the two sync however the data allows. This video shows what each side optimizes for and where the split pays.

Topics covered:

  • The unified model's problem: one shape for writes, reads, and reports
  • Commands: mutations expressed as intents, not data edits
  • Queries: read models shaped for screens, joins, and projections
  • The sync path: same database, event stream, or read replica
  • Why CQRS pairs with event sourcing: the write model as an event log
  • Projections: building the read model from events instead of triggers
  • The consistency trade: eventual consistency between models and its costs
  • When CQRS is overkill: CRUD apps and single-model systems

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