Components

Component Selection Guide

🗄️Database Selection

Use CaseBest ChoiceWhy
Transactions, relationshipsPostgreSQL / MySQLACID, complex queries, joins
Flexible schema, documentsMongoDBSchema flexibility, horizontal scale
High write throughputCassandra / ScyllaDBWrite-optimized, distributed
Key-value, simple lookupsDynamoDB / RedisSimple, fast, scalable
Full-text searchElasticsearchInverted index, fast search
Time-series dataInfluxDB / TimescaleDBTime-based queries, aggregations
Graph relationshipsNeo4jTraversal, social graphs

⚡Caching Solutions

Redis

  • ✓ Rich data structures (lists, sets, hashes)
  • ✓ Pub/sub, Lua scripting
  • ✓ Persistence options
  • Best for: Session storage, leaderboards, rate limiting

Memcached

  • ✓ Simple key-value
  • ✓ Multi-threaded
  • ✓ Lower memory overhead
  • Best for: Simple caching, large objects

📬Message Queues

ToolStrengthsBest For
KafkaHigh throughput, replay, orderingEvent streaming, logs, analytics
RabbitMQFlexible routing, reliabilityTask queues, complex routing
SQSManaged, simple, reliableAWS apps, decoupling services

📦Storage Solutions

Object Storage

S3, GCS, Azure Blob

Images, videos, backups, static assets

Block Storage

EBS, Persistent Disk

Database storage, VM disks

CDN

CloudFront, Cloudflare

Static content, global distribution

Quick Decision Rules

  • • Need transactions? → SQL database
  • • Need speed? → Add caching layer (Redis)
  • • Need async processing? → Add message queue
  • • Need to scale writes? → Consider sharding or NoSQL
  • • Need search? → Elasticsearch alongside main DB
Back-of-Envelope NumbersTrade-off Decision Matrix