Apart from the fields that are used to hold data, we can store additional information along with the documents. We already talked about different mapping options and what data type we can use. We would like to discuss in more detail some functionalities of Elasticsearch that are not used every day, but can make your life easier when it comes to data handling.
Each of the field types discussed in the following sections should be defined on an appropriate type level—they are not index wide
As you may recall, each document indexed in Elasticsearch has its own identifier and type. In Elasticsearch, there are two types of internal identifiers for the documents.