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

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

Redis vs Memcached

Installation Guides

Windows Systems

1. Download from Microsoft Archive
2. Run:

   1	redis-server.exe redis.windows.conf

3. Connect:

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   redis-cli

Ubuntu Systems

1. Install:

   1	sudo apt-get install redis-server

2. Start/Stop:

   1 2	sudo service redis-server start sudo service redis-server stop

Remote Access Configuration

Modify redis.conf:

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bind 0.0.0.0  # Allow all network interfaces

Core Operations

Basic Commands

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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

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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

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

Hash Operations

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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

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

Pub/Sub System

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

Persistence Configuration

Enable in redis.conf:

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

Best Practices

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

Command Reference:

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