Couchbase 5.5 introduces automatic hash partitioning for indexes, enhancing the capacity, queriability, and performance of database queries. This feature allows a single logical index to be partitioned into multiple physical index partitions across data nodes, utilizing more disk, memory, and CPU resources. Users create hash-partitioned indexes with simple syntax by adding a PARTITION BY clause in the index definition, which facilitates parallel processing and efficient query execution. The system supports complex queries, including those with equality predicates that benefit from partition pruning, and enhances performance through parallel scans and aggregations. This approach contrasts with manual partitioning methods in earlier versions, providing a more streamlined and efficient indexing process. Additionally, Couchbase's scale-out architecture supports a flexible number of partitions and nodes, optimizing resource allocation and improving total cost of ownership without necessitating a direct correlation between partition count and node count.