Aerospike Server 4.9 introduces new functionality and enhancements, including the HyperLogLog (HLL) probabilistic data type for efficient distinct-counting operations. The HLL data type allows developers to perform cardinality calculations on sets of data with significantly reduced storage requirements compared to brute-force methods. Additionally, Aerospike 4.9 introduces Scan by Partition feature, which enables parallel scanning at the partition level for improved performance. Changes in eviction/expiration defaults have been made to better align with common use cases, and the max-records option has been added as an alternative to percent sampling for basic scans. The Request/Response Compression Level has also been reduced to improve CPU usage without compromising efficiency.