Search is hard, and it becomes harder when both speed and relevancy are required together. There are lots of configurable options Elasticsearch provides out-of-the-box to take control before you start putting the data into it. Elasticsearch is schemaless. I gave a brief idea in the previous chapter of why it is not completely schemaless and how it creates a schema right after indexing the very first document for all the fields existing in that document. However, the schema matters a lot for a better and more relevant search. Equally important is understanding the theory behind the phases of document indexing and search.
In this chapter, we will cover the following topics: