Elastic Search Mapping

Elastic Search  Mapping 

Mapping defines how the document and its fields are stored and indexed.
You can add a mapping to existing index with PUT API
You may define multiple mappings for a given index. However if the mapping has the same fields they map to the same field internally.

Create a mapping :  

Mapping is similar to a schema in relational DB.
This command create a mapping for the index - test_index and type - test_type.
Dynamic - strict specify there are strict checks. Any new field added it will throw an exception.

PUT test_index
{
  "mappings": {
    "test_type": {
      "dynamic": "strict",
      "properties": {
        "car_number": {
          "type": "string"
        },
        "manufacturer": {
          "type": "string"
        }
      }
    }
  }
}

Edit an existing mapping -

Adding a new field to an existing type. Suppose you want to add the car model to the test_type.
This will fail as dynamic : strict is set in the mapping.
In order to edit the mapping :

PUT test_index/_mapping/test_type
{
  "properties": {
    "car_model": {
      "type": "string"
    }
  }
}

Get a mapping - 

For very large json objects it may be simple to create a mapping by inserting an entry into the a type and then extract the mapping using the below command.

GET /test_index/_mapping/test_type