redis-lists-sets

name	redis-lists-sets
description	Master Redis Lists and Sets - queues, stacks, unique collections, set operations, and real-world implementation patterns
sasmp_version	1.3.0
bonded_agent	02-redis-data-structures
bond_type	PRIMARY_BOND
version	2.1.0
last_updated	2025-01
parameters	{"key":{"type":"string","required":true,"pattern":"^[a-zA-Z0-9:_-]+$"},"operation":{"type":"string","required":true,"enum":["push","pop","range","members","add","remove","set_ops"]},"blocking":{"type":"boolean","required":false,"default":false},"timeout_seconds":{"type":"integer","required":false,"default":30,"max":300}}
retry_config	{"max_retries":3,"backoff_strategy":"exponential","backoff_base_ms":100,"retryable_errors":["connection_timeout","BUSY"]}
observability	{"metrics":["list_length","set_cardinality","operation_latency_ms","blocking_wait_time"]}

Redis Lists and Sets Skill

Lists Overview

Redis Lists are linked lists of string values, perfect for queues and stacks.

List Commands

# Push operations
LPUSH key value [value ...]   # Push to head - O(1) per element
RPUSH key value [value ...]   # Push to tail - O(1) per element

# Pop operations
LPOP key [count]              # Pop from head - O(N)
RPOP key [count]              # Pop from tail - O(N)
BLPOP key [key ...] timeout   # Blocking pop - O(1)
BRPOP key [key ...] timeout   # Blocking pop from tail

# Range operations
LRANGE key start stop         # Get range - O(S+N)
LINDEX key index              # Get by index - O(N)
LLEN key                      # Get length - O(1)

# Manipulation
LMOVE source dest LEFT|RIGHT LEFT|RIGHT
LINSERT key BEFORE|AFTER pivot value
LSET key index value          # Set by index
LTRIM key start stop          # Trim list
LPOS key element              # Find position (Redis 6.0.6+)

Sets Overview

Redis Sets are unordered collections of unique strings.

Set Commands

# Basic operations
SADD key member [member ...]   # Add members - O(N)
SREM key member [member ...]   # Remove members - O(N)
SMEMBERS key                   # Get all members - O(N)
SISMEMBER key member           # Check membership - O(1)
SMISMEMBER key member [member ...]  # Multi-check (Redis 6.2+)
SCARD key                      # Get cardinality - O(1)

# Random operations
SRANDMEMBER key [count]        # Random members
SPOP key [count]               # Pop random members

# Set operations
SINTER key [key ...]           # Intersection - O(N*M)
SUNION key [key ...]           # Union - O(N)
SDIFF key [key ...]            # Difference - O(N)
SINTERSTORE dest key [key ...] # Store intersection
SUNIONSTORE dest key [key ...] # Store union
SDIFFSTORE dest key [key ...]  # Store difference

# Scanning
SSCAN key cursor [MATCH pattern] [COUNT count]

Production Patterns

Pattern 1: Reliable Message Queue

# Producer
RPUSH queue:tasks '{"id":1,"action":"process","retry":0}'

# Consumer with reliability (move to processing)
LMOVE queue:tasks queue:processing LEFT RIGHT

# After processing complete
LREM queue:processing 1 '{"id":1,"action":"process","retry":0}'

# Dead letter queue for failures
RPUSH queue:dlq '{"id":1,"action":"process","error":"timeout"}'

Pattern 2: Priority Queue

# High priority
LPUSH queue:tasks:high '{"priority":"high"}'

# Normal priority
RPUSH queue:tasks:normal '{"priority":"normal"}'

# Consumer checks high first
BLPOP queue:tasks:high queue:tasks:normal 30

Pattern 3: Unique Visitors Tracking

# Track unique visitors per day
SADD visitors:2024-01-15 "user:123"
SADD visitors:2024-01-15 "user:456"

# Count unique
SCARD visitors:2024-01-15

# Weekly unique visitors (union)
SUNIONSTORE visitors:week:3 visitors:2024-01-15 visitors:2024-01-16 visitors:2024-01-17
SCARD visitors:week:3

# Set TTL for automatic cleanup
EXPIRE visitors:2024-01-15 604800  # 7 days