Using explicit mapping allows you to be faster when you start inserting data using a schema-less approach, without being concerned about the field types. Therefore, in order to achieve better results and performance when indexing, it's necessary to manually define a mapping.
Fine-tuning the mapping has some advantages, as follows:
Reduces the size of the index on disk (disabling functionalities for custom fields)
Indexes only interesting fields (a general boost to performance)
Precooks data for a fast search or real-time analytics (such as aggregations)
Correctly defines whether a field must be analyzed in multiple tokens or whether it should be considered as a single token
ElasticSearch also allows you to use base fields with a wide range of configurations.
You need a working ElasticSearch cluster and an index named test (refer to the Creating an index recipe in Chapter 4, Basic Operations) where you can put the mappings.