Mapping is a very important concept in Elasticsearch, as it defines how the search engine should process a document and its fields.
Search engines perform the following two main operations:
- Indexing: This is the action to receive a document and to process it and store it in an index
- Searching: This is the action to retrieve the data from the index
These two parts are strictly connected; an error in the indexing step leads to unwanted or missing search results.
Elasticsearch has explicit mapping on an index level. When indexing, if a mapping is not provided, a default one is created, and guesses the structure from the data fields that the document is composed of. This new mapping is then automatically propagated to all cluster nodes.
The default type mapping has sensible default values, but when you want to change their behavior or customize several other aspects...