Spring Data Couchbase has transitioned from using the 1.4 generation of the Couchbase Java SDK to the 2.2 SDK, which supports N1QL, a new query language for documents. The 2.x SDK is a complete rewrite, featuring a fully asynchronous layer and RxJava Observables, which necessitates a major version update for Spring Data Couchbase. Key improvements include enhanced configuration elements aligned with Couchbase's structure, support for N1QL as the default for repository methods, and the ability to execute reduce functions through query derivation. Users can also configure consistency levels for queries to balance performance and data accuracy. The update allows for customization of JSON type information fields to improve compatibility with Couchbase Mobile, and it aligns the SDK configuration closer to Couchbase's cluster terminology. Overall, these changes enhance flexibility, performance, and integration within the Spring Data Couchbase framework.