Redis CLI and Data Structures: From Basics to Mastery

A compact guide for running Redis locally, understanding its core data structures, and practicing with CLI commands.

Diagram showing how Redis typically works

What is Redis?

Redis is an in-memory data store used as a fast database and cache to quickly store and retrieve data.

How Redis Works

Client (your app) sends request. Example: "Give me user data".
Check Redis (cache) first. If data is already in Redis, return it instantly.
If not in Redis, fetch data from database (DB).
Store that data in Redis (cache).
Send data back to client.
Next time same request, data is already in Redis and is fast.

In one line: Client -> Redis (cache) -> if not found -> DB -> save in Redis -> return to client.

Why Use Redis?

Very fast (in-memory).
Reduces load on database.
Perfect for caching, sessions, and real-time apps.

How to Start the Project

You can run the entire application (Node.js server + Redis Stack) using Docker Compose:

# Start the application
docker-compose up --build

App Server: http://localhost:3000
RedisInsight GUI: http://localhost:8001

Docker Redis Setup

# Run Redis Stack container with RedisInsight UI
docker run -d --name redis-stack -p 6379:6379 -p 8001:8001 redis/redis-stack:latest

# Access the container terminal (optional)
docker exec -d -it redis-stack bash

# Launch Redis CLI inside container
redis-cli

Redis Server port: 6379
RedisInsight GUI: http://localhost:8001

Redis Data Types Documentation

To learn more about Redis data types and their implementations, see the Official Redis Documentation.

Simple key-value pairs.

When to use: Store simple values by key.

Use case: OTP codes, user session token, feature flags.

SET key value - Set the value of a key
GET key - Get the value of a key
DEL key - Delete a key
APPEND key value - Append a value to a key

Collections of string elements sorted by insertion order.

When to use: Maintain ordered items with push and pop operations.

Use case: Recent activity feed, task queue, chat message buffer.

LPUSH key value - Prepend an element
RPUSH key value - Append an element
LPOP key - Remove the first element
LRANGE key start stop - Get a range of elements

Unordered collections of unique strings.

When to use: Track unique values without duplicates.

Use case: Unique website visitors, user tags, permissions per user.

SADD key member - Add members to a set
SMEMBERS key - Get all members in a set
SISMEMBER key member - Check membership
SREM key member - Remove members

Unique strings ordered by an associated score.

When to use: Rank items and query by score.

Use case: Leaderboards, priority queues, trending content ranking.

ZADD key score member - Add or update members
ZRANGE key start stop - Return a range of members
ZREM key member - Remove members
ZRANK key member - Find member index

Append-only data structure suitable for message brokering.

When to use: Keep ordered event logs and let consumers read events.

Use case: Event pipeline, order processing, background worker communication.

XADD key ID field string - Append to a stream
XRANGE key start end - Return a range of elements
XREAD COUNT count STREAMS key ID - Read streams
XLEN key - Return entry count

Coordinates and distance calculations.

When to use: Store locations and run proximity searches.

Use case: Nearby stores, delivery radius, ride-hailing nearest driver search.

GEOADD key longitude latitude member - Add items
GEOPOS key member - Get member coordinates
GEODIST key member1 member2 - Distance between members
GEOSEARCH key FROMMEMBER member BYRADIUS radius - Query within radius