Couchbase Map-Reduce Views and N1QL with GSI are two services that handle different use cases in the Couchbase data platform. Couchbase Map-Reduce Views were used to handle previously handled use cases, now handled by N1QL and GSI Indexing. N1QL is a declarative query language inspired by SQL, which enables flexible and composable queries for JSON data, while using 4-valued boolean logic. It has built-in support for grouping, aggregation, and caching, with features like scatter-gather indexing and memory-optimized indexes. In contrast, Couchbase Map-Reduce Views are based on user-defined map() and reduce() functions that operate on data in the background, allowing complex logic within those functions. The scalability of N1QL is higher than Couchbase Map-Reduce Views due to independent scaling via Multidimensional scaling (MDS).