This article demonstrates how to use the Couchbase SDK for Java to access data from a MongoDB dataset in a Couchbase cluster. The code samples show how to connect to the Couchbase cluster, perform key/value operations, execute secondary lookups via N1QL queries, and update an existing document using sub-document operations. The article also covers more advanced topics such as batching, reactive querying, and N1QL data access with secondary lookups. The goal is to provide a comprehensive guide on how to migrate MongoDB data to Couchbase using the Java SDK.