Node.js
/Intermediate
Redis
Definition
Remote Dictionary Server. An open-source, in-memory, key-value data store used as a database, cache, message broker, and queue.
Explain Like I'm New
Standard databases (like MongoDB or PostgreSQL) save data to a Hard Drive. Hard drives are safe, but slow. Redis saves data entirely in RAM (Memory). RAM is volatile (wiped if the server restarts), but it is insanely, blazingly fast. Because it's so fast, developers use Redis as the middleman Cache sitting in front of the main database.
Real World Example
Storing User Sessions or JWT Blacklists. Because every single API request requires checking if the user is authenticated, doing a slow SQL query on every request destroys performance. Storing session data in Redis allows sub-millisecond authentication.
Common Use Cases
- •High-speed caching
- •Session management
- •Pub/Sub real-time messaging
- •Leaderboards
Interactive Example
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Interview Questions
basic
- Does Redis store data on a Hard Drive or in RAM?
intermediate
- Why not just use a JavaScript Object `const cache = {}` instead of Redis?