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# Connect to local Redis server
redis-cli

# Connect to remote Redis server
redis-cli -h hostname -p port -a password

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# Check server status
PING                # Returns PONG if Redis is running
INFO                # Detailed server information
FLUSHALL            # Clear all keys from all databases
FLUSHDB             # Clear keys from the current database

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# Basic Key Management
SET key value           # Set a key with a value
GET key                 # Retrieve a key's value
DEL key                 # Delete a key
EXISTS key              # Check if key exists
EXPIRE key seconds      # Set expiration for a key
TTL key                 # Check time-to-live for a key
KEYS pattern            # Find keys matching a pattern (use cautiously)

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# String Commands
SET user:1000 "John Doe"            # Set a string value
SETNX key value                     # Set if not exists
SETEX key seconds value             # Set with expiration
MSET key1 value1 key2 value2        # Set multiple keys
MGET key1 key2                      # Get multiple keys
INCR counter                        # Increment integer value
DECR counter                        # Decrement integer value
APPEND key value                    # Append to existing string
STRLEN key                          # Get string length

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# List Commands
LPUSH mylist value                  # Push to left side of list
RPUSH mylist value                  # Push to right side of list
LPOP mylist                         # Remove and return left-most item
RPOP mylist                         # Remove and return right-most item
LRANGE mylist 0 -1                  # List all elements
LLEN mylist                         # Get list length
LINDEX mylist 2                     # Get element at specific index

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# Set Commands
SADD myset member1 member2          # Add members to set
SMEMBERS myset                      # List all set members
SINTER set1 set2                    # Intersection of sets
SDIFF set1 set2                     # Difference between sets
SUNION set1 set2                    # Union of sets
SISMEMBER myset member              # Check if member exists
SCARD myset                         # Count set members

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# Hash Commands
HSET user:1000 name "John" age 30   # Set hash fields
HGET user:1000 name                 # Get specific hash field
HGETALL user:1000                   # Get all hash fields and values
HMSET user:1000 name "John" age 30  # Set multiple hash fields
HINCRBY user:1000 age 1             # Increment hash field
HDEL user:1000 name                 # Delete hash field

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# Sorted Set Commands
ZADD leaderboard 100 user1 200 user2    # Add with score
ZRANGE leaderboard 0 -1                 # List all members
ZRANK leaderboard user1                 # Get member's rank
ZREVRANGE leaderboard 0 9               # Top 10 members
ZSCORE leaderboard user1                # Get member's score

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# Publish/Subscribe
SUBSCRIBE channel                   # Subscribe to a channel
PUBLISH channel message             # Publish a message
UNSUBSCRIBE channel                 # Unsubscribe from channel

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# Transactions
MULTI                   # Start transaction
SET key1 value1
SET key2 value2
EXEC                    # Execute transaction

# Pipelining (in client library)
pipeline = redis.pipeline()
pipeline.set('key1', 'value1')
pipeline.get('key1')
results = pipeline.execute()

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-- Lua Script Example
redis.call('SET', 'counter', 10)
local value = redis.call('GET', 'counter')
return value

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# Persistence Modes
# RDB (point-in-time snapshots)
SAVE                   # Create immediate snapshot
BGSAVE                 # Background save

# AOF (append-only file)
CONFIG SET appendonly yes
CONFIG SET appendfsync everysec

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# Memory Management
CONFIG SET maxmemory 2gb            # Set memory limit
CONFIG SET maxmemory-policy allkeys-lru  # Eviction policy

# Performance Tips
- Use appropriate data structures
- Minimize key sizes
- Use pipelining
- Avoid expensive operations on large datasets

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# Cache Aside Pattern
def get_user(user_id):
    user = redis.get(f'user:{user_id}')
    if not user:
        user = database.get_user(user_id)
        redis.setex(f'user:{user_id}', 3600, user)
    return user

# Rate Limiting
def is_allowed(user_id):
    key = f'rate_limit:{user_id}'
    current = redis.incr(key)
    if current == 1:
        redis.expire(key, 60)  # Reset after 1 minute
    return current <= 10  # 10 requests per minute