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)

- #14524 `XREADGROUP CLAIM` returns strings instead of integers
- #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)

- #14480, #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