The latest release of Couchbase Server 5.5 introduces several key indexing improvements, including partitioned indexes that enable automatic splitting and spreading of index nodes across multiple smaller nodes, reducing the need for manual splitting and improving performance. Additionally, aggregation pushdown to indexes allows for faster N1QL queries by pushing down aggregations like COUNT, SUM, MIN, MAX, AVG along with GROUP BY, while the new "ALTER INDEX" command simplifies administration by providing a declarative way to move indexes between nodes. The revamped Index Administration Console offers better readability and visual cues, and new REST endpoints provide insights into index usage parameters, enabling administrators to monitor and optimize their indexes more effectively.