Yashotantra Academy logo
← System Design theorytheory 0/5 · 0%
level 1
Curious · 0 XP
streak
0d
perfect
0
badges
0

100 XP to Apprentice

Performance · medium

4. Caching and Cache Invalidation

Reducing latency and database load with deliberate cache policies.

1 min read3 questionsup to 50 XPtopic 4/5

Read in another language

AI translates the explanation and quiz text while preserving code and answer scoring.

A cache stores frequently requested results closer to the caller. Cache-aside lets the application read and populate the cache, while write-through updates the cache and database together.

Every cache needs an expiration or invalidation strategy. TTLs limit staleness, while request coalescing, jittered TTLs, and stale-while-revalidate help prevent a cache stampede when many requests rebuild one expired key at once.

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
  4. 4. Read every explanation, even for the answers you got right.

Scoring

  • · Up to 30 XP from quiz accuracy.
  • · +15 XP for a perfect first attempt.
  • · +5 XP while a 3-day streak is running.
  • · 75% or higher marks the topic complete.

Check your understanding

  1. 1. What happens in the cache-aside pattern after a cache miss?

  2. 2. What is a cache stampede?

  3. 3. What is the main trade-off of a longer cache TTL?

Badges

First light
Pass your first topic
Sharp shooter
3 perfect first-try quizzes
On a roll
Study 3 days in a row
Week warrior
Study 7 days in a row
Grinder
Earn 500 XP
Deep diver
Earn 1500 XP