Valkey 9.1 Deep Dive — Database-Level ACLs, Lua-as-a-Module, and a New I/O Threading Model Hitting 2.1M RPS, Plus HGETDEL/MSETEX/CLUSTERSCAN Redefining the 2026 In-Memory Datastore Operations Standard TL;DR Valkey 9.1.0 (May 19, 2026) is the first minor release after the 9.0 GA, with 80+ contributors hardening security, observability, performance, efficiency, and tooling all at once. Numbered database-level ACLs let you scope a user's permissions to specific databases ( db=0,1 ), making single-cluster multi-tenant isolation practical. Lua moved to a module ( libvalkeylua.so ) — pure cache workloads can drop Lua entirely and shrink the attack surface to zero. A redesigned I/O threading model pushes a single server to 2.1M RPS (512-byte payloads, 9 IO threads, pipeline depth 10) and gives up to 17% more throughput. New commands HGETDEL / MSETEX / CLUSTERSCAN , JSON logging ( log-format json ), main/IO thread usage metrics, and TLS auto-reload + SAN-URI mTLS round it out.…