Couchbase 4.5 introduces significant enhancements in array indexing, allowing for more efficient querying and indexing of individual elements within arrays in NoSQL documents. This update addresses challenges faced in previous versions, such as the inefficiency of indexing entire arrays as single scalar values, which made specific data searches cumbersome and storage-intensive. By supporting partial indexes, nested arrays, and operators like DISTINCT ARRAY, Couchbase 4.5 enables more precise and compact indexing, improving query performance by allowing targeted indexing of array subsets. This enhancement results in a substantial performance boost, exemplified by a test where an array index query performed nearly nine times faster than a traditional index. The new features offer improved query processing and flexibility, as users can now create indexes on specific elements or attributes within arrays, optimizing storage space and search efficiency.