System Design

Template

• Template

Components

• SQL vs NoSQL
• NoSQL

Consensus

• Zookeeper’s ZAB
• Raft (etcd)
• Paxos

Availability Patterns

• Availability Patterns

Replication

• Replication

Strategies

• Write Ahead Logs (WAL) Or ARIES

  • Appends operations to a log on disk before executing them in the database.
  • Can be improved with Low-water mark (a worker that checks which part of the log can be deleted)
  • And segmented log (segments the log into smaller pieces)

• Back of the Envelope Numbers

Example Web Tier