Alex Brasetvik's article on Elasticsearch, originally known as Found and now Elastic Cloud, delves into the distributed nature of Elasticsearch by focusing on how requests are processed within a cluster. It explains how Elasticsearch handles index and search requests, detailing the roles of different nodes such as data, master, and client nodes in a cluster, as well as the responsibilities of the request coordinator node. The article illustrates the process of routing requests to the appropriate shards, the mechanics of index operations involving primary and replica shards, and the role of the transaction log in ensuring data durability. It also covers search request processing through shard routing, query rewriting, and the scatter/gather approach to retrieve results efficiently. Additionally, the article clarifies the abstractions of mappings and types in Elasticsearch and their transformation into Lucene documents, shedding light on the boundaries between Elasticsearch and Lucene technologies.