Here is a summary of the article in one paragraph: MongoDB 4.2 will introduce Wildcard Indexes, which allow for automatic matching and indexing of any field, sub-document, or array in a collection, with flexible filtering options. This feature can simplify schema design and improve search performance in polymorphic data patterns, such as product catalogs, e-commerce, social media, and IoT applications. Wildcard Indexes support covered queries, collation, and immediacy, and are updated synchronously with changes to the data. The new index creation command uses `$**` to specify a wildcard index on a field or its subdocuments, allowing for flexible indexing of variable document structures. With Wildcard Indexes, users can consolidate query types against MongoDB 4.2, simplifying platform architecture and reducing performance impact from multiple indexes.