Couchbase's unique NoSQL database combines cache and storage technology, widely used for storing binary data and JSON documents. To properly size a production system, determining the average document size is essential, which can be achieved using views in a development or staging system, though not recommended for production due to the indexing overhead. Views in Couchbase are written in JavaScript and help extract, filter, and aggregate data, beginning with a map function to create an index of key/value pairs, and optionally a reduce function to perform calculations like counting, summing, and averaging document sizes. A map function example is provided, demonstrating how to emit document sizes using JSON.stringify for JSON documents and decodeBase64 for binary documents. A corresponding reduce function aggregates these sizes to calculate an average, showcasing Couchbase's map and reduce constructs, although users report issues with this method in Couchbase version 5.1.