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AWS AmazonElastiCache documentation change

Service: AmazonElastiCache · 2026-07-01 · Documentation low

File: AmazonElastiCache/latest/dg/engine-versions.md

Summary

Added documentation for Valkey 9.1 engine version including new features like memory optimizations, new commands (HGETDEL, MSETEX, CLUSTERSCAN), and database-level ACL access control.

Security assessment

The change introduces documentation for database-level ACL access control, which is a security feature enabling fine-grained permissions. However, there's no evidence this addresses a specific security vulnerability; it's a new capability.

Diff

diff --git a/AmazonElastiCache/latest/dg/engine-versions.md b/AmazonElastiCache/latest/dg/engine-versions.md
index bfd39cb53..85c0811d3 100644
--- a//AmazonElastiCache/latest/dg/engine-versions.md
+++ b//AmazonElastiCache/latest/dg/engine-versions.md
@@ -7 +7 @@
-Valkey 9.0Valkey 8.2Valkey 8.1Valkey 8.0ElastiCache version 7.2.6 for ValkeySupported Redis OSS versionsRedis OSS versions end of life scheduleSupported Memcached versions
+Valkey 9.1Valkey 9.0Valkey 8.2Valkey 8.1Valkey 8.0ElastiCache version 7.2.6 for ValkeySupported Redis OSS versionsRedis OSS versions end of life scheduleSupported Memcached versions
@@ -12,0 +13,19 @@ This section covers the supported Valkey, Memcached, and Redis OSS engines and h
+## ElastiCache version 9.1 for Valkey
+
+Here are some of the new features introduced in Valkey 9.1 (compared to ElastiCache Valkey 9.0):
+
+  * **Up to 20% memory reduction for common string patterns** – Strings under 128 bytes now use 20% less memory. Sorted sets see up to a 10% memory reduction. Bulk delete operations (SREM, ZREM, HDEL) pause auto-shrink during bulk ops for faster execution.
+
+  * **HGETDEL, MSETEX, and CLUSTERSCAN commands** – Three new commands: `HGETDEL` atomically retrieves and deletes hash fields, `MSETEX` sets multiple keys with a shared expiration in a single call, and `CLUSTERSCAN` provides cluster-wide key scanning across all nodes.
+
+  * **Database-level ACL access control** – Per-database permissions via `ACL SETUSER ... db=0,1` syntax give you fine-grained access control at the database level for multi-tenant workloads on a single cluster.
+
+  * Over 70 additional enhancements including reduced rehashing latency spikes, CLUSTER SHARDS availability-zone field, HSETEX NX/XX flags, hardware clock enabled by default, JSON logging format, and main/IO thread cumulative usage metrics through INFO ALL. For the complete list, see [Valkey 9.1 Release Notes](https://github.com/valkey-io/valkey/releases/tag/9.1.0).
+
+
+
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+For more information on Valkey, see [Valkey](https://valkey.io/).
+
+For more information on the Valkey 9.1 release, see [Valkey 9.1 Release Notes](https://github.com/valkey-io/valkey/releases/tag/9.1.0).
+