Valkey Application Developer Reference

Routing

• Conditional update, compare-and-swap, optimistic locking, CAS, WATCH/MULTI/EXEC replacement, lock release race, safe delete, atomic delete-if-equal, replace Lua script -> Conditional Ops (IFEQ/DELIFEQ)
• Per-field TTL, hash field expiration, session tokens, feature flags -> Hash Field TTL
• Slow commands, large requests/replies, monitoring, debugging -> COMMANDLOG
• Key expiration inspection, absolute timestamps, TTL audit, PERSIST -> EXPIRETIME
• Polygon queries, geofencing, region matching -> Geospatial
• Cluster numbered databases, atomic slot migration -> Cluster Enhancements
• I/O threading, SIMD, zero-copy, dual-channel replication -> Performance Internals
• Caching, write-through, write-behind, stampede, client-side caching -> Patterns (caching)
• Sessions, sliding TTL, multi-device, session store -> Patterns (sessions)
• Distributed locks, Redlock, safe release -> Patterns (locks)
• Rate limiting, throttling, token bucket, sliding window -> Patterns (rate-limiting)
• Queues, streams, XADD, XREAD, consumer groups, dead letter, FIFO -> Patterns (queues)
• Leaderboards, rankings, sorted set, top-N, pagination -> Patterns (leaderboards)
• Pub/Sub, publish, subscribe, notifications, fan-out, sharded pub/sub -> Patterns (pubsub-patterns)
• Search, autocomplete, prefix, inverted index, tag filtering -> Patterns (search-autocomplete)
• Counters, atomic increment, HyperLogLog, idempotency, sharded counters -> Patterns (counters)
• Key naming, memory, performance, persistence, cluster, HA -> Best Practices
• Memory fragmentation, mem_fragmentation_ratio, active defrag, jemalloc, MEMORY USAGE, MEMORY DOCTOR -> Advanced (defrag)
• Replication internals, PSYNC, partial resync, full resync, backlog sizing, diskless replication, dual-channel, replica priority, min-replicas-to-write -> Advanced (replication)
• Latency diagnosis, high p99, LATENCY LATEST, LATENCY DOCTOR, latency-monitor-threshold, slow commands, fork pauses, THP, event loop -> Advanced (latency)
• Auth, ACLs, TLS, network security -> Security
• Common mistakes, KEYS in production, missing TTL, unbounded collections -> Anti-Patterns
• Redis compatibility, migration, fork history -> Overview
• Data types, strings, hashes, lists, sets, sorted sets, streams, bitmaps, geo, HyperLogLog -> Basics (data-types)
• Transactions, MULTI/EXEC, Lua scripting, EVAL, FCALL, INFO, SCAN, CONFIG -> Basics (server-and-scripting)
• EVAL vs FCALL, EVALSHA, FUNCTION LOAD, Lua script replication, determinism, EVAL_RO, FCALL_RO, busy-script-time, lua-time-limit, script timeout, SCRIPT KILL, sliding window rate limiter, CAS Lua -> Advanced (lua-functions)
• CLIENT TRACKING, RESP3 push invalidation, RESP2 redirect, BCAST mode, OPTIN, OPTOUT, tracking-table-max-keys, redis:invalidate, GLIDE cache, redis-py tracking, ioredis tracking, invalidation consistency -> Advanced (client-side-caching)

Valkey-Specific Features

Topic	Reference
SET IFEQ (8.1+), DELIFEQ (9.0+) - atomic compare-and-swap, safe lock release without Lua	conditional-ops
HSETEX, HGETEX, HGETDEL, HEXPIRE, HPERSIST (9.0+) - per-field TTL on hashes	hash-field-ttl
COMMANDLOG GET/LEN/RESET (8.1+) - unified slow/large-request/large-reply logging, replaces SLOWLOG	commandlog
EXPIRETIME, PEXPIRETIME, PERSIST - absolute expiration timestamps, TTL inspection and removal	expiretime
GEOSEARCH BYPOLYGON (9.0+) - arbitrary polygon region matching	geospatial
Numbered databases in cluster mode, atomic slot migration	cluster-enhancements
I/O threading, SIMD acceleration, prefetch, zero-copy, dual-channel replication	performance-summary

Overview

Topic	Reference
Valkey versions, license, governance, Redis fork history, Valkey vs Redis comparison	what-is-valkey
Redis compatibility, migration strategies, what changed	compatibility

Application Patterns

Topic	Reference
Cache-aside, write-through, write-behind, client-side caching, stampede prevention	caching-strategies
Cache invalidation, TTL patterns, eviction policies	caching-invalidation
Session hashes, sliding TTL, session rotation, basic session store	sessions-basics
Per-field TTL sessions (Valkey 9.0+), session counting, concurrent session limits	sessions-field-expiry
SET NX with TTL, safe release (DELIFEQ), Redlock algorithm, fencing tokens, lock renewal	locks
Fixed window, sliding window counter, sliding window log	rate-limiting-windows
Token bucket, per-field rate limiting (Valkey 9.0+), algorithm comparison	rate-limiting-advanced
Simple FIFO queues (LPUSH/BRPOP), reliable queues (LMOVE)	queues-list-based
Stream-based queues (XREADGROUP), consumer groups, dead letter, priority queues, queue pattern comparison	queues-streams
Sorted set rankings, pagination, top-N, score updates, composite scoring, time-bucketed	leaderboards
Pub/Sub patterns, sharded pub/sub, fan-out, notification systems, keyspace notifications, pub/sub vs streams comparison	pubsub-patterns
Prefix autocomplete, tag filtering, inverted indexes, scored search results	search-autocomplete
Atomic counters, sharded counters, idempotency keys	counters-atomic
HyperLogLog, BITFIELD packed counters, deduplication strategies	counters-approximate

Best Practices

Topic	Reference
Key naming, namespaces, hot key and big key avoidance, key expiration strategies, key analysis commands	keys
Memory reduction, encoding thresholds, TTL strategies, eviction	memory
UNLINK vs DEL, SCAN vs KEYS, data-type iteration	performance-commands
Pipelining, connection pooling, I/O threading, performance anti-patterns	performance-throughput
RDB, AOF, hybrid persistence, latency impact, durability decisions	persistence
Hash tags, cross-slot errors, CROSSSLOT fixes	cluster-hash-tags
MOVED/ASK redirects, replica reads, pipelining in cluster, CLUSTERSCAN	cluster-operations
Sentinel, failover, retries, WAIT/WAITAOF, replication lag, Sentinel vs Cluster decision	high-availability

Advanced Topics

Topic	Reference
Memory fragmentation, mem_fragmentation_ratio, active defrag config, MEMORY USAGE, MEMORY DOCTOR, Valkey 8.1 hashtable impact	defrag
Replication internals (PSYNC2), partial vs full resync triggers, backlog sizing, diskless sync, dual-channel replication (8.0+), replica chains, min-replicas-to-write	replication-internals
End-to-end latency diagnosis, LATENCY LATEST/HISTORY/DOCTOR, COMMANDLOG correlation, fork pauses, THP, expiration storms, I/O thread impact, p99 playbook	latency-diagnosis
EVAL vs FCALL, EVALSHA, FUNCTION LOAD, script replication (effects vs commands), determinism, EVAL_RO/FCALL_RO for replica reads, busy-script-time, SCRIPT KILL, memory limits, SET IFEQ/DELIFEQ as Lua replacements, sliding window rate limiter	lua-functions
CLIENT TRACKING protocol (RESP3 push, RESP2 redirect), default/BCAST/OPTIN/OPTOUT modes, tracking-table-max-keys eviction, GLIDE CacheConfig, redis-py/ioredis manual wiring, consistency guarantees, connection management, what to track vs skip	client-side-caching

Security

Topic	Reference
ACL users, key pattern restrictions, TLS encryption, security checklist	auth-and-acl

Anti-Patterns

Topic	Reference
KEYS in production, DEL on big keys, missing maxmemory, hot keys, unbounded collections, severity guide, detection commands	quick-reference

Basics

Topic	Reference
Strings, Hashes, Lists, Sets, Sorted Sets, Streams, Pub/Sub, HyperLogLog, Bitmaps, Geo	data-types
Transactions (MULTI/EXEC), Lua scripting (EVAL/FCALL), Server commands (INFO/SCAN/CONFIG), client management, monitoring	server-and-scripting