This is the General Availability release of Redis 8.4 in Redis Open Source.

Major changes compared to 8.2

• DIGEST, DELEX; SET extensions - atomic compare-and-set and compare-and-delete for string keys
• MSETEX - atomically set multiple string keys and update their expiration
• XREADGROUP - new CLAIM option for reading both idle pending and incoming stream entries
• CLUSTER MIGRATION - atomic slot migration
• CLUSTER SLOT-STATS - per-slot usage metrics: key count, CPU time, and network I/O
• Redis query engine: FT.HYBRID - hybrid search and fused scoring
• Redis query engine: I/O threading with performance boost for search and query commands (FT.*)
• I/O threading: substantial throughput increase (e.g. >30% for caching use cases (10% SET, 90% GET), 4 cores)
• JSON: substantial memory reduction for homogenous arrays (up to 91%)

Binary distributions

• Alpine and Debian Docker images - https://hub.docker.com/_/redis
• Install using snap - see https://github.com/redis/redis-snap
• Install using brew - see https://github.com/redis/homebrew-redis
• Install using RPM - see https://github.com/redis/redis-rpm
• Install using Debian APT - see https://github.com/redis/redis-debian

Operating systems we test Redis 8.4 on

• Ubuntu 22.04 (Jammy Jellyfish), 24.04 (Noble Numbat)
• Rocky Linux 8.10, 9.5
• AlmaLinux 8.10, 9.5
• Debian 12 (Bookworm), Debian 13 (Trixie)
• macOS 13 (Ventura), 14 (Sonoma), 15 (Sequoia)

Bug fixes (compared to 8.4-RC1)

• Fix XREADGROUP CLAIM to return delivery metadata as integers #14524 XREADGROUP CLAIM returns strings instead of integers
• Add variable key-spec flags to SET IF* and DELEX #14529 Add variable key-spec flags to SET IF* and DELEX
• #P928 Potential memory leak (MOD-11484)
• #T1801, #T1805 macOS build failures (MOD-12293)
• #J1438 JSON.NUMINCRBY - wrong result on integer array with non-integer increment (MOD-12282)
• #J1437 Thread safety issue related to ASM and shared strings (MOD-12013)

Performance and resource utilization improvements (compared to 8.4-RC1)

• Optimize stream ID comparison and endian conversion hot paths #14480, Introduce copy-free version streamPropagateXCLAIM to reduce allocation overhead in stream propagation #14516 Optimize XREADGROUP

known bugs and limitations

• When executing FT.SEARCH, FT.AGGREGATE, FT.CURSOR, FT.HYBRID, TS.MGET, TS.MRANGE, TS.MREVRANGE and TS.QUERYINDEX while an atomic slot migration process is in progress, the results may be partial or contain duplicates
• FT.PROFILE, FT.EXPLAIN and FT.EXPLACINCLI doesn’t contain the FT.HYBRID option
• Metrics from FT.HYBRID command aren’t displayed on FT.INFO and INFO
• Option EXPLAINSCORE, SHARD_K_RATIO, YIELD_DISTANCE_AS and WITHCURSOR with FT.HYBRID are not available
• Post-filtering (after COMBINE step) using FILTER is not available
• Currently the default response format considers only key_id and score, this may change for delivering entire document content