System Design

Caching Strategies

System DesignCachePerformance

Caching strategies are fundamental to system design for reducing latency and load.

The 4 Core Patterns

📖

Cache-Aside (Lazy Load)

Application checks cache first. On miss, fetches from DB, then stores in cache for next time.

Most CommonRead-HeavyStale OK

Use case:User profiles, product catalogs, session data

Latency:Cache miss = DB latency + cache write

🔄

Read-Through

Cache library handles loading from DB automatically on miss. App only talks to cache.

Simpler CodeAuto-populateRead-Heavy

Use case:CMS content, configuration data, reference lookups

Latency:Cache miss = automatic DB fetch (transparent)

✍️

Write-Through

Writes go to cache first, then immediately sync to DB. Cache is always consistent with DB.

Strong ConsistencySlower WritesRead-Heavy

Use case:Financial transactions, inventory levels, booking systems

Latency:Write = cache write + DB write (sequential)

⚡

Write-Behind (Write-Back)

Writes go to cache first, then async batch to DB later. Fastest writes, eventual consistency.

Fastest WritesWrite-HeavyData Risk

Use case:Analytics events, logging, leaderboards, activity feeds

Latency:Write = cache write only (DB async)

See It In Action

Interact with the patterns to see how data flows between components

Waiting...

Cache-Aside: Read Flow (Miss → Hit)

📱APP

Application

⚡CACHE

Redis Cache

🗄️DB

Database

1. App checks cache for key "user:123"

2. Cache returns MISS — key not found

3. App queries database for user data

4. Database returns user data

5. App writes data to cache with TTL

6. App returns response to client

— Next request: Cache HIT (immediate return)

Cache Hit

Cache Miss

Active Request

Pattern Comparison

Choose the right strategy based on your consistency and performance requirements

Pattern	Read Perf	Write Perf	Consistency	Complexity	Risk
Cache-Aside					✓ None
Read-Through					✓ None
Write-Through					✓ None
Write-Behind					✗ High

Resources

Title	Type	Link
Caching Strategies and Patterns	web	Open
System Design - Caching	youtube	Open
Redis: Caching Patterns	web	Open
Caching Strategies for High Performance	course	Open

Guide Contributors

ObydulSenior Software Engineer

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The 4 Core Patterns

📖

Cache-Aside (Lazy Load)

Application checks cache first. On miss, fetches from DB, then stores in cache for next time.

Most CommonRead-HeavyStale OK

Use case:User profiles, product catalogs, session data

Latency:Cache miss = DB latency + cache write

🔄

Read-Through

Cache library handles loading from DB automatically on miss. App only talks to cache.

Simpler CodeAuto-populateRead-Heavy

Use case:CMS content, configuration data, reference lookups

Latency:Cache miss = automatic DB fetch (transparent)

✍️

Write-Through

Writes go to cache first, then immediately sync to DB. Cache is always consistent with DB.

Strong ConsistencySlower WritesRead-Heavy

Use case:Financial transactions, inventory levels, booking systems

Latency:Write = cache write + DB write (sequential)

⚡

Write-Behind (Write-Back)

Writes go to cache first, then async batch to DB later. Fastest writes, eventual consistency.

Fastest WritesWrite-HeavyData Risk

Use case:Analytics events, logging, leaderboards, activity feeds

Latency:Write = cache write only (DB async)

See It In Action

Interact with the patterns to see how data flows between components

Waiting...

Cache-Aside: Read Flow (Miss → Hit)

📱APP

Application

⚡CACHE

Redis Cache

🗄️DB

Database

1. App checks cache for key "user:123"

2. Cache returns MISS — key not found

3. App queries database for user data

4. Database returns user data

5. App writes data to cache with TTL

6. App returns response to client

— Next request: Cache HIT (immediate return)

Cache Hit

Cache Miss

Active Request

Pattern Comparison

Choose the right strategy based on your consistency and performance requirements

Pattern	Read Perf	Write Perf	Consistency	Complexity	Risk
Cache-Aside					✓ None
Read-Through					✓ None
Write-Through					✓ None
Write-Behind					✗ High

Resources

Title	Type	Link
Caching Strategies and Patterns	web	Open
System Design - Caching	youtube	Open
Redis: Caching Patterns	web	Open
Caching Strategies for High Performance	course	Open

Guide Contributors

ObydulSenior Software Engineer