Redis Open Source 8.6 release notes
===================================

--------------------------------------------------------------------------------
Upgrade urgency levels:

LOW:      No need to upgrade unless there are new features you want to use.
MODERATE: Program an upgrade of the server, but it's not urgent.
HIGH:     There is a critical bug that may affect a subset of users. Upgrade!
CRITICAL: There is a critical bug affecting MOST USERS. Upgrade ASAP.
SECURITY: There are security fixes in the release.
--------------------------------------------------------------------------------

The release notes contain PRs from multiple repositories:

#n - Redis (https://github.com/redis/redis)
#Qn = Query Engine (https://github.com/RediSearch/RediSearch)
#Jn = JSON (https://github.com/RedisJSON/RedisJSON)
#Tn = Time Series (https://github.com/RedisTimeSeries/RedisTimeSeries)
#Pn = Probabilistic (https://github.com/RedisBloom/RedisBloom)


================================================================================
Redis 8.6.1    Released Mon 23 Feb 2026 10:00:00 IST
================================================================================

SECURITY: There is a security fix in the release

### Security fixes

- A user can manipulate data read by a connection by injecting \r\n sequences into a Redis error reply

### Bug fixes

- #14785 `HOTKEYS`: The `INFO` command may display module information, and the missing `HOTKEYS HELP` subcommand has been added
- #14789 Bug in RDB loading prevented hash table expansion, increasing load time


================================================================
Redis 8.6 GA (8.6.0)    Released Tue 10 Feb 2026 16:00:00 IST
================================================================

This is the General Availability release of Redis 8.6 in Redis Open Source.

### Major changes compared to 8.4

- Substantial performance improvements
- Substantial memory reduction for hashes (hashtable-encoded) and sorted sets (skiplist-encoded)
- Streams: `XADD` idempotency (at-most-once guarantee) with new `IDMPAUTO` and `IDMP` arguments
- New eviction policies - least recently modified: `volatile-lrm` and `allkeys-lrm`
- Hot keys detection and reporting; new command: `HOTKEYS`
- TLS certificate-based automatic client authentication
- Time series: support NaN values; new aggregators: `COUNTNAN` and `COUNTALL`

### 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 8.6 on

- Ubuntu 22.04 (Jammy Jellyfish), 24.04 (Noble Numbat)
- Rocky Linux 8.10, 9.5
- AlmaLinux 8.10, 9.5, 10.1
- Debian 12 (Bookworm), Debian 13 (Trixie)
- macOS 14 (Sonoma), 15 (Sequoia)

### New Features (compared to 8.6-RC1)

- #14695 Keys memory size histograms

### Performance and resource utilization improvements (compared to 8.6-RC1)

- #14714 Optimize user ACL permission verification
- #14692 Optimize peak memory metric collection
- #14739 Avoid allocating and releasing list node in reply copy avoidance
- #14713 Reduce per command syscalls by reusing cached time when hardware monotonic clock is available
- #14726 Optimize `XREADGROUP CLAIM`
- #13962 Vector set: replace manual popcount with __builtin_popcountll for binary vector distance (Intel, AMD, ARM)
- #14474 Vector set: vectorized the quantized 8-bit vector distance calculation (Intel, AMD)
- #14492 Vector set: vectorize binary quantization path for vectorsets distance calculation (Intel, AMD)

### Configuration parameters

- #14719 `cluster-slot-stats-enabled` - per-slot resource consumptions statistics to collect
- #14695 `key-memory-histograms` collect memory consumption histograms per data type

### Metrics

- #14695 `db0_distrib_lists_sizes`, `db0_distrib_sets_sizes`, `db0_distrib_hashes_sizes`, `db0_distrib_zsets_sizes`

### Known bugs and limitations

- Streams: avoid using `XADD` with the new `IDMP` or `IDMPAUTO` options when using `appendonly yes` with `aof-use-rdb-preamble no` (non default)
  This limitation will be removed in the next patch.

================================================================
Redis 8.6-RC1 (8.5.240)    Released Thu 22 Jan 2025 17:00:00 IST
================================================================

This is the first Release Candidate of Redis 8.6 in Redis Open Source.

Release Candidates are feature-complete pre-releases. Pre-releases are not suitable for production use.

### 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 8.6 on

- Ubuntu 22.04 (Jammy Jellyfish), 24.04 (Noble Numbat)
- Rocky Linux 8.10, 9.5, 10.1
- AlmaLinux 8.10, 9.5, 10.1
- Debian 12 (Bookworm), Debian 13 (Trixie)
- 14 (Sonoma), 15 (Sequoia)

### New Features (compared to 8.4.0)

- #14615 Streams: `XADD` idempotency (at-most-once guarantee) with new `IDMPAUTO` and `IDMP` arguments
- #14624 New eviction policies - least recently modified: `volatile-lrm` and `allkeys-lrm`
- #14680 Hot keys detection and reporting; new command: `HOTKEYS`
- #14610 TLS certificate-based automatic client authentication
- #T1853 Time series: support NaN values; new aggregators: `COUNTNAN` and `COUNTALL`

### Security and privacy fixes

- #14645 Hide Personally Identifiable Information from ACL log
- #14659 ACL: Key-pattern bypass in `MSETEX`
- #T1837, #J1474 Hide Personally Identifiable Information from server log
- #P950 Out-of-bounds read when loading an invalid RDB file (MOD-12802)

### Bug fixes (compared to 8.4.0)

- #14545 ACL: AOF loading fails if ACL rules are changed and don't allow some commands in `MULTI`-`EXEC`
- #14637 Atomic slot migration: wrong adjacent slot range behavior
- #14567 Atomic slot migration: support delay trimming slots after finishing migrating slots
- #14623 Streams: `XTRIM`/`XADD` with approx mode (`~`) don’t delete entries for `DELREF`/`ACKED` strategies
- #14552 Streams: Incorrect behavior when using `XDELEX...`ACKED` after `XGROUP DESTROY`
- #14537 `SCAN`: restore original filter order (revert change introduced in 8.2)
- #14581 Rare server hang at shutdown
- #14597 Panic when cluster node is uninitialized
- #14583 `FLUSHALL ASYNC` on a writable replica may block the main thread for an extended period
- #14504 Cluster: fix race condition in broadcast configuration
- #14416 Fixed argument position handling in Redis APIs
- #T1784, #T1839, #P952, #J1477 Atomic slot migration support
- #P946 `MEMORY USAGE`: fix reported value (MOD-12799)
- #J1473 Adding escapes to already-escaped characters (MOD-8137)
- #J1475 `JSON.CLEAR` does not error if more than one path is specified (MOD-13109)

### Performance and resource utilization improvements (compared to 8.4.0)

- #14608 Reply copy-avoidance path to reduce memory copies for bulk string replies
- #14595 Hash: unify field name and value into a single struct
- #14701 Sorted set: unify score and value into a single struct
- #14662 Optimize listpack iterator on hash fields
- #14699 Optimize set commands with expiration
- #14700 Optimize prefetching
- #14715 Optimize prefetch sizing logic
- #14636 Optimize `ZRANK`
- #14676 Utilize hardware clock by default on ARM AArch64
- #14575 Disable RDB compression when diskless replication is used

### Modules API

- #14445
  - `RM_CreateKeyMetaClass` - define a new key-metadata class
  - `RM_ReleaseKeyMetaClass` - release a key-metadata class
  - `RM_SetKeyMeta` - attach or update a metadata value for a key under a specific metadata-key class
  - `RM_GetKeyMeta` - get a metadata value for a key under a specific metadata-key class

### Configuration parameters

- #14624 `maxmemory-policy`: new eviction policies: `volatile-lrm`, `allkeys-lrm`
- #14615 `stream-idmp-duration`, `stream-idmp-maxsize` - defaults for streams idempotent production
- #14610 `tls-auth-clients-user` TLS certificate-based automatic client authentication
- #14596 `flushdb` option for `repl-diskless-load`: always flush the entire dataset before diskless load

### Metrics

- #14610 `acl_access_denied_tls_cert` - failed TLS certificate–based authentication attempts

### known bugs and limitations

- Reids Query Engine: In case of load rebalancing operations (such as Atomic Slot Migration) taking place during the lifetime of a cursor,
  there is a chance that some results may be missing.

