Introduction

Mapping is an important concept in ElasticSearch, as it defines how the search engine should process a document.

Search engines perform two main operations:

• Indexing: This is the action to receive a document and store/index/process it in an index

• Searching: This is the action to retrieve data from the index

These two operations are closely connected; an error in the indexing step can lead to unwanted or missing search results.

ElasticSearch has explicit mapping on an index/type level. When indexing, if a mapping is not provided, a default mapping is created by guessing the structure from the data fields that compose the document. Then, this new mapping is automatically propagated to all the cluster nodes.

The default type mapping has sensible default values, but when you want to change their behavior or customize several other aspects of indexing (storing, ignoring, completion, and so on), you need to provide a new mapping definition.

In this chapter, we'll see all the possible types...