Whenever we want to extract fields from JSON documents without the document ID, we use views. If you want to find a document or fetch information about a document with attributes or fields of a document other than the document ID, a view is the way to do it. Views are written in the form of MapReduce, which we have discussed earlier, that is, it consists of the map and reduce phase. Couchbase implements MapReduce using the JavaScript language.

The following diagram shows you how various documents are passed through the View Engine to produce an index. The view engine ensures that all documents in the bucket are passed through the map method for processing and subsequently to the reduce function to create indexes:

The View Engine

When we write views, the view engine defines materialized views for JSON documents and then queries across the dataset in the bucket. Couchbase provides a view processor to process entire documents with the map and reduce methods defined by the developer to create...