Tutorials Software Architect Tutorial
CAP Theorem in Practice
CAP Theorem in Practice: free step-by-step lesson with examples, common mistakes, and interview tips — part of Software Architect Tutorial on Toolliyo Academy.
On this page
Software Architect Tutorial · Lesson 22 of 100
CAP Theorem in Practice
Foundations & Styles ✓ → Distributed & Data → Cloud & Quality → Leadership & Cases
Distributed & Data · 2 — Structure · ~6 min · Distributed Systems
What is this?
CAP says under network partition you choose availability or consistency for that operation — not both at once. Real systems pick per use case.
Why should you care?
Architects design different paths: payments lean consistent; feeds lean available.
See it live — copy this example
These are architecture exercises: fill templates, draw boxes, write ADRs. No cloud bill required.
# Per-use-case table
Checkout payment authorize -> prefer consistency (CP-ish)
Home feed read -> prefer availability (AP-ish)
Inventory decrement -> careful consistency + idempotencyWhat happened?
- Do not “pick CAP for the whole company”.
- Pick per request type and document it.
Practice next
- List 3 your platform operations.
- Mark each C-priority or A-priority under partition.
- Note user-visible behavior when the dependency is down.
- Add a fourth operation: search.
- Define a degraded mode banner.
Remember
CAP is per operation under partition. UX must match the choice. Timeouts are part of the design.
Partition drill
Payment DB unreachable.
Outcome: Orders pause; catalog still reads from cache.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
Sign in to ask a question or upvote helpful answers.
No questions yet — be the first to ask!