Does ElasticSearch have a schema?
Yes, Elastic search can have a schema. A schema is a description of one or more fields that describes the document type and how to handle the different fields of a document. The schema in Elasticsearch is a mapping that describes the fields in the JSON documents along with their data type, as well as how they should be indexed in the Lucene indexes that lie under the hood. Because of this, in Elasticsearch terms, we usually call this schema a “mapping”.
Elasticsearch has the ability to be schema-less, which means that documents can be indexed without explicitly providing a schema. If you do not specify a mapping, Elasticsearch will by default generate one dynamically when detecting new fields in documents during indexing.