Valkey 9.2.0-rc2 introduces Zstd compression and forkless replication

Valkey has released 9.2.0-rc2, the second release candidate for its upcoming 9.2.0 major version. This update focuses on enhancing data persistence efficiency and improving multi-threaded performance through new compression codecs and synchronization methods.

Key improvements include the addition of Zstd as a streaming compression codec for RDB persistence and replication, as well as support for forkless full synchronization to replicas. The release also addresses several memory leaks and performance bottlenecks in sorted set operations and client-side caching tracking.

Technical improvements in Valkey 9.2.0-rc2

• Persistence and Replication: Adds Zstd support for RDB files to provide better compression ratios than LZ4 and allows compressed RDB preambles to be reused directly as AOF bases.
• Synchronization Architecture: Introduces forkless full synchronization, enabling the server to serve disk and diskless full syncs from a background-thread snapshot without requiring a process fork.
• Command and Data Structures: Implements the new DELEX command for conditional string deletion and optimizes sorted set operations (ZPOPMIN, ZPOPMAX, ZSCAN) for B+tree and listpack encodings.
• Memory and I/O Efficiency: Reduces false sharing in per-thread memory counters and IO thread activity to improve throughput on SMT x86 systems, while fixing a memory leak in the client-side caching tracking table.
• Security and Cryptography: Updates ACL GENPASS and hash function seeding to utilize the configured OpenSSL 3 provider when built with TLS, ensuring compatibility with validated crypto modules.

Why it matters

These updates provide system administrators with more efficient storage and replication options, reducing CPU and I/O overhead during heavy workloads. The introduction of forkless synchronization and improved Zstd compression is particularly beneficial for high-availability deployments and large-scale cloud-native database environments.