System Design cards
In a network partition, a distributed system must choose between strong consistency and availability.
CAP theorem basics
Indexes speed up common queries, but they cost extra storage and slower writes.
Database indexing in system design
Sharding splits data across multiple databases so one machine does not hold or serve everything.
Database sharding basics
Queues decouple producers from consumers so work can be retried, smoothed, and processed asynchronously.
How do message queues help system design?
A primary handles writes while replicas serve copied data, often improving read scale and availability.
Primary-replica database setup
Rate limiting controls how many requests a client can make in a window to protect system stability and fairness.
Rate limiting basics
Scalability is how well a system handles growth, while latency is how quickly one request gets a response.
Scalability vs latency
A CDN caches content closer to users so static or cacheable responses arrive with lower latency.
What is a CDN?
A load balancer distributes traffic across multiple instances to improve availability and throughput.
What is a load balancer?
Eventual consistency means replicas may temporarily disagree, but if updates stop they converge over time.
What is eventual consistency?