Valkey 9.2 Release Candidate Adds Forkless RDB Snapshots, ACL Roles, and a New Path Hash Data Type
The first release candidate of Valkey 9.2 introduces fork-free backups, reusable ACL roles, a radix-tree Path Hash type, and a B+ tree for large sorted sets.
Overview
The Valkey project has published 9.2.0-rc1, the first release candidate of Valkey 9.2, adding forkless RDB snapshots, a reusable ACL-roles system, a new radix-tree-backed data type called Path Hash, and a switch from skiplists to B+ trees for large sorted sets. The release notes, published September 16, 2026, rate the upgrade urgency as low, noting it is “the first release candidate of Valkey 9.2.0.”
Valkey is an open-source fork of Redis that emerged after Redis Ltd. changed its licensing terms; the project describes itself as “an open source (BSD) high-performance key/value datastore that supports a variety of workloads such as caching, message queues, and can act as a primary database,” according to valkey.io. “The project is backed by the Linux Foundation, ensuring it will remain open source forever,” the site states. The Machine Herald previously covered the release of Valkey 9.1 in June, which added database-level ACLs and a redesigned I/O threading model. Valkey 9.2 builds on that release with a broader set of persistence, security, and data-structure changes.
What We Know
Forkless RDB snapshots. The release adds forkless RDB snapshots, described in the release notes as opt-in “via the new forkless-infrastructure-enabled and bgsave-default-method configs, with new INFO persistence fields reporting the save method and progress,” according to the 9.2.0-rc1 release notes.
ACL roles. The release adds “named, reusable sets of ACL selectors managed with ACL SETROLE/DELROLE/GETROLE/ROLES and assigned to users with role:<name>, in commands, the ACL file and valkey.conf,” according to the release notes. A separate addition, the ACL DIGEST command, “returns a fingerprint of the ACL rules currently in effect, useful to verify what ACL LOAD applied,” the notes say.
Path Hash, a new data type. The candidate introduces “Path Hash, a new radix-tree-backed data type with PH* commands for exact lookup, longest-prefix matching, and prefix traversal over binary-safe paths,” according to the release notes.
B+ tree replaces skiplist for large sorted sets. The notes state that “large sorted sets are now backed by a B+ tree instead of a skiplist,” and that the OBJECT ENCODING command now “reports btree instead of skiplist” for those keys, according to the release notes.
Hot key detection. The release adds “server-side hot key detection with new HOTKEYS GET/RESET commands, enabled by setting hotkeys-top-k,” according to the release notes.
Streams, TLS, and other additions. The candidate adds the XACKDEL and XDELEX stream commands, described as supporting “KEEPREF, DELREF and ACKED modes to acknowledge and delete messages once consumer groups no longer need them,” the release notes say. It also adds support for a secondary TLS certificate “via tls-alt-cert-file, tls-alt-key-file and tls-alt-key-file-pass, e.g. a post-quantum certificate alongside RSA, with matching INFO TLS fields,” and whole-stream LZ4 compression of RDB files “via the new rdbcompression lz4 option,” with the notes specifying that “the default per-string LZF behavior is unchanged,” according to the release notes. A new INCREX command was also added “to atomically increment a key by an integer or float while setting its expiration, with NX/XX conditions,” per the same source.
Performance changes. The release notes list several efficiency improvements, including SIMD-optimized radix tree lookups using “SIMD-optimized memchr() for child-edge search,” a claim that exact XTRIM MAXLEN = 0 operations are now “about 2.5x” faster by “clearing the whole stream in one step instead of removing entries individually,” and an extension of memory prefetching “to hash, set and sorted set member lookups when io-threads are enabled,” which the notes say improves performance for “30 field/member commands on large keys.” MEMORY PURGE was also changed to release “free pages from the glibc main arena back to the OS,” according to the release notes.
A behavior change to watch. The release notes flag one behavior change: “active expiration of keys and hash fields now increments the dirty counter, so save points (and thus BGSAVE) may trigger more often,” according to the release notes.
Security-relevant fix. Among the listed bug fixes, the release notes describe a fix to SORT key extraction “so a STORE destination named like an option can no longer bypass ACL checks and write to an unauthorized key,” according to the release notes.
What We Don’t Know
The release notes do not give a target date for a stable, non-candidate 9.2.0 build, and Valkey’s project blog had not published a companion announcement post for 9.2 as of this release candidate. Because 9.2.0-rc1 is explicitly a release candidate rather than a stable release, some of the listed features and configuration names could still change before a general-availability build ships.
Analysis
The headline additions in this candidate target two long-standing operational pain points for Redis-family databases: fork-based persistence and coarse-grained access control. Traditional background saves in this family of databases rely on forking the server process to write a consistent snapshot, an approach that can strain memory on very large datasets. The new forkless RDB path, gated behind the forkless-infrastructure-enabled and bgsave-default-method configs, is opt-in in this candidate rather than a default, according to the release notes. Similarly, the addition of ACL roles alongside the existing per-user ACL model gives operators a way to define permission sets once and reuse them across many users rather than repeating selector rules per account, per the same source. Whether these opt-in mechanics become defaults will likely depend on feedback gathered during the release-candidate cycle.