Couchbase's multi-model capabilities make it an attractive choice for IoT use cases like sensor data updates. To ensure that new sensor readings are only stored if they have a later timestamp than the previous reading, developers can consider various approaches such as using optimistic or pessimistic locking with the key-value API, ACID transactions, SQL++ UPDATE queries, or Eventing. Each approach has its pros and cons, including trade-offs in terms of performance, complexity, and requirements. Optimistic locking is a straightforward approach that works well when conflicts are infrequent, while pessimistic locking provides a "safer" approach but requires understanding the performance implications of locking. ACID transactions offer reliability but come with overhead, while SQL++ UPDATE queries provide a familiar declarative approach but have query parsing and execution overhead. Eventing allows for close-to-the-data logic consolidation but has additional overhead due to eventing service and extra collections. Ultimately, the best approach depends on factors such as update frequency, concurrency, and performance requirements, which can be determined through real-world testing with live data or a good approximation of it.