If you don't want to control the ID generation for the documents, you can use the POST method.
The format of this request is POST /<index>/<type>, with the JSON document as the body of the request:
POST /catalog/_doc
{
"sku": "SP000003",
"title": "Mastering Elasticsearch",
"description": "Mastering Elasticsearch",
"author": "Bharvi Dixit",
"price": 54.99
}
The ID, in this case, will be generated by Elasticsearch. It is a hash string, as highlighted in the response:
{
"_index" : "catalog",
"_type" : "_doc",
"_id" : "1ZFMpmoBa_wgE5i2FfWV",
"_version" : 1,
"result" : "created",
"_shards" : {
"total" : 2,
"successful" : 1,
"failed" : 0
},
"_seq_no" : 4,
"_primary_term" : 1
}
As per pure REST conventions, POST is used for creating a new resource and PUT is used for updating an existing resource. Here, the usage of PUT is equivalent to saying I know the ID that I want to assign, so use this ID while indexing this document.