Cache puzzle
Cache reads without lying
A profile service has many repeated reads, occasional edits, and users expect profile changes to appear within a minute.
Puzzle target
Choose a cache pattern with freshness control and a clear invalidation path.
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Complete each design choice to unlock the review. The feedback above will point out what your current tradeoff misses.
Flash cards
Review the key moves
What is the main idea behind System Design: Caching Strategy?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Put the learning moves in the order that makes the concept easiest to apply.
System design is a sequence of explicit tradeoffs. Start small: clarify the goal, estimate load, pick the simplest architecture, then name what breaks first.
| Design surface | What you decide |
|---|---|
| Requirements | Functional behavior, constraints, and non-goals |
| Scale | Reads, writes, storage, bandwidth, and latency target |
| Architecture | Clients, load balancer, services, cache, database, queue, and workers |
| Reliability | Failure mode, fallback, retry, and metric |
| Goal | Use cache only when the read pattern, freshness tolerance, and invalidation path are clear. |
Practice Task
- Choose cache-aside, TTLs, and invalidation rules for a read-heavy endpoint.
- Use the design puzzle below to choose components and tradeoffs.
- Explain the bottleneck before adding more infrastructure.