The Advisor function in Couchbase Server 6.5 extends its capabilities from advising on a single query to managing index recommendations for multiple query workloads and supporting session handling. When applied to a workload, it analyzes queries, provides index recommendations, and outputs current, recommended, and recommended covering indexes. The session handling allows users to define specific queries, collect them over time, and asynchronously analyze them for index recommendations. Users can manage these sessions with various actions such as starting, stopping, or purging sessions. While the Advisor function offers a structured approach to optimizing query performance through index analysis, there is an ongoing effort to enhance its functionality and performance based on user feedback.