dynamic
默认情况下，字段可以被动态地添加到一条文档或者其内部对象中，只需索引一条包含新的字段文档即可。例如:
PUT my_index/_doc/1
{
"username": "johnsmith",
"name": {
"first": "John",
"last": "Smith"
}
}
GET my_index/_mapping
PUT my_index/_doc/2
{
"username": "marywhite",
"email": "[email protected]",
"name": {
"first": "Mary",
"middle": "Alice",
"last": "White"
}
}
GET my_index/_mapping