The text provides a comprehensive overview of the implementation of ACID transactions in Couchbase and the challenges faced by NoSQL and NewSQL databases in maintaining data consistency across distributed systems. It highlights the differences between relational, NewSQL, and NoSQL databases in terms of atomicity, emphasizing the efficiency of using semi-structured data like JSON in document databases to minimize cross-node joins and enhance performance. Couchbase's architecture allows for a masterless setup with no central transaction coordinator, enabling efficient distributed transactions managed by the client-side, thus avoiding a single point of failure. The document details how Couchbase employs Active Transaction Records (ATRs) and Check And Set (CAS) operations to ensure data consistency and durability, even during node failures, and discusses the use of N1QL for distributed SQL transactions. Ultimately, the article argues that these features make Couchbase a leading choice for handling transactions at scale in NoSQL environments, with flexibility and minimal performance impact.