Redis Essentials: Features, Setup, and Operations

Introduction

Redis is a distributed in-memory NoSQL database supporting persistence. It offers rich data structures including strings, lists, sets, sorted sets, and hashes.

Key Features:

Memory-based with optional disk persistence
Distributed architecture support
Multi-data structure support
Pub/Sub messaging system

Official Documentation: http://redisdoc.com

Use Cases

Session Storage: Persistent login sessions
Rankings/Counters: Real-time leaderboards, article view counters
Message Queues: Task queue systems (e.g., Celery integration)
Real-time Metrics: Active user tracking
Data Caching: Frequently accessed data (e.g., forum sections)
Social Features: Friend relationships (used by Weibo)
Pub/Sub Systems: Chat applications

Redis vs Memcached

Feature	Memcached	Redis
Storage Type	Pure In-Memory	Memory + Disk Sync
Data Types	Fixed Value Types	Multiple Structures
Virtual Memory	❌ Not Supported	✔️ Supported
Data Persistence	❌ No	✔️ Dump File Backup
Disaster Recovery	❌ No	✔️ Memory Restoration
Pub/Sub	❌ No	✔️ Supported

Installation Guides

Windows Systems

Download from Microsoft Archive
Run:
```
redis-server.exe redis.windows.conf
```
Connect:
```
redis-cli
```

Ubuntu Systems

Install:
```
sudo apt-get install redis-server
```

Start/Stop:

sudo service redis-server start
sudo service redis-server stop

Remote Access Configuration

Modify redis.conf:

bind 0.0.0.0  # Allow all network interfaces

Core Operations

Basic Commands

SET key value          # Add key-value pair
DEL key               # Delete key
EXPIRE key 60         # Set 60-second expiration
TTL key               # Check remaining expiration
KEYS *                # List all keys

List Operations

LPUSH list1 "item1"    # Add to list head
RPUSH list1 "item2"   # Add to list tail
LRANGE list1 0 -1     # Get all elements
LREM list1 2 "value"  # Remove two occurrences
LLEN list1            # Get list length

Set Operations

SADD set1 "A" "B"      # Add elements
SMEMBERS set1          # View all elements
SREM set1 "A"          # Remove element
SINTER set1 set2       # Find intersections

Hash Operations

HSET user:1001 name "John"  # Create hash
HGET user:1001 name        # Get value
HGETALL user:1001         # Get all fields
HDEL user:1001 email      # Delete field

Advanced Features

Transactions

MULTI                  # Start transaction
SET balance 100
SET credit 50
EXEC                   # Commit transaction
DISCARD                # Cancel transaction
WATCH key1             # Monitor key changes

Pub/Sub System

PUBLISH news "Update"  # Send message to channel
SUBSCRIBE news         # Receive messages

Persistence Configuration

Enable in redis.conf:

save 900 1     # Save if 1+ changes in 15min
save 300 10    # Save if 10+ changes in 5min

Best Practices

Use connection pooling for high traffic
Monitor memory usage with INFO MEMORY
Implement proper key expiration policies
Use AOF (Append-Only File) for critical data
Regularly backup RDB snapshots

Command Reference:

redis-cli INFO SERVER   # View server metrics
BGSAVE                  # Create background snapshot

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