
# Redis 8.2

What's new in Redis 8.2

Redis 8.2 builds on the foundation of Redis 8.0 with significant performance and memory optimizations, enhanced streaming capabilities, and improved cluster management tools.

This release delivers major improvements across multiple areas:

*   Enhanced Redis Streams with new commands for better consumer group management
*   New bitmap operations for advanced bit manipulation
*   Advanced cluster monitoring with per-slot usage metrics
*   Optimized vector search with new compression algorithms
*   Enhanced keyspace notifications with new event types
*   More than 15 performance and resource utilization improvements

Below is a detailed breakdown of these updates.

## Security improvements

Redis 8.2 includes important security fixes:

*   **CVE-2025-27151**: Fixed potential stack overflow and RCE vulnerability in redis-check-aof.
*   **CVE-2025-32023**: Fixed out-of-bounds write vulnerability in HyperLogLog commands.
*   **CVE-2025-48367**: Improved connection handling to retry accepting connections even when errors occur.

## New features

### Enhanced Redis Streams

Redis 8.2 introduces powerful new commands that simplify consumer group management and stream lifecycle operations:

*   [`XDELEX`](/docs/latest/commands/xdelex/): Delete entries from streams with advanced consumer group handling options.
*   [`XACKDEL`](/docs/latest/commands/xackdel/): Acknowledge and delete stream entries in a single atomic operation.

These commands include `KEEPREF`, `DELREF`, and `ACKED` options that give you precise control over how consumer group references are handled during entry deletion. This simplifies common patterns where you need to clean up acknowledged entries while working with multiple consumer groups.

The [`XADD`](/docs/latest/commands/xadd/) and [`XTRIM`](/docs/latest/commands/xtrim/) commands have also been extended with these same options, providing consistent behavior across all commands that remove stream entries.

### Cluster monitoring improvements

The new [`CLUSTER SLOT-STATS`](/docs/latest/commands/cluster-slot-stats/) command provides detailed per-slot usage metrics including:

*   Key count per slot
*   CPU time consumption
*   Network ingress and egress

This enhanced visibility helps you optimize cluster performance and identify hotspots in your data distribution.

### Vector search enhancements

The `VSIM` command now supports the `IN` operator for filtering expressions, giving you more flexibility when performing vector similarity searches with complex filtering criteria.

### Enhanced bitmap operations

Redis 8.2 extends the [`BITOP`](/docs/latest/commands/bitop/) command with new operators that provide more sophisticated bit manipulation capabilities:

*   **DIFF**: Perform bitwise difference operations between bitmaps.
*   **DIFF1**: Calculate the difference with optimized single-bit operations.
*   **ANDOR**: Combine AND and OR operations in a single command.
*   **ONE**: Specialized operation for single-bit scenarios.

These new operators enable more complex bitmap workflows and can simplify operations that previously required multiple commands.

### Improved keyspace notifications

Redis 8.2 introduces new keyspace notification event types that provide better visibility into data changes:

*   **OVERWRITTEN**: Triggered when a key's value is completely overwritten.
*   **TYPE\_CHANGED**: Fired when a key's data type changes.

These events help you build more responsive applications by providing granular notifications about specific types of data modifications.

## Improvements

Redis 8.2 delivers substantial performance improvements across core operations.

### Performance optimizations

*   **BITCOUNT**: Enhanced with prefetching optimizations for faster bit counting operations.
*   **SCAN**: Optimized to perform expiration checks only on databases with volatile keys, reducing unnecessary overhead.
*   **List operations**: `LREM`, `LPOS`, and `LINSERT` benefit from cached `string2ll` results in `quicklistCompare`.
*   **Sorted set operations**: `ZRANK` and related commands use the same caching optimizations.
*   **Key operations**: `COPY`, `RENAME`, and `RESTORE` are optimized when TTL is used.
*   **Client management**: Reduced overhead in client cron operations to avoid blocking the main thread.
*   **Vector operations**: Improved RDB loading and RESTORE speed for vector sets by storing worst link information.

### Memory efficiency improvements

*   **JSON data types**: Memory footprint improvements through number inlining.
*   **Memory tracking**: Reduced overhead associated with tracking malloc's usable memory.
*   **Expiry handling**: Optimized expiry checks in scan callbacks.
*   **Vector compression**: Additional compression variants for the SVS-VAMANA vector index reduce memory usage.

### Vector search performance

Redis 8.2 introduces the `SHARD_K_RATIO` parameter for KNN vector queries in Redis clusters. This unstable feature allows you to favor network latency over accuracy, providing faster responses when exact precision isn't critical.

### Enhanced metrics

Redis 8.2 provides new metrics to help you monitor and troubleshoot your Redis instances.

#### Memory metrics

*   `used_memory_peak_time`: Timestamp when `used_memory_peak` was reached

#### Replication metrics

*   `master_current_sync_attempts`: Number of sync attempts since last disconnection
*   `master_total_sync_attempts`: Total number of sync attempts to master
*   `master_link_up_since_seconds`: Duration since the replication link was established
*   `total_disconnect_time_sec`: Cumulative time the replica has been disconnected

These metrics provide better visibility into replication health and help you identify patterns in connection stability.

## Component versions

Redis 8.2 continues the unified distribution approach introduced in Redis 8.0, delivering all functionality in a single Redis Open Source package without separate modules.

## On this page
