After reading the previous section, we now know how querying works in Elasticsearch. You know that Elasticsearch, in most cases, needs to scatter the query across multiple nodes, get the results, merge them, fetch the relevant documents from one or more shards, and return the final results to the client requesting the documents. What we didn't talk about are two additional things that define how queries behave: search type and query execution preference. We will now concentrate on these functionalities of Elasticsearch.
Elasticsearch is a distributed search engine and so all functionality provided must be distributed in its nature. It is exactly the same with querying. Because we would like to discuss some more advanced topics on how to control the query process, we first need to know how it works.
Let's now get back to how querying works. We started the theory in the first chapter and we would like to get back to it. By default, if we don't alter...