Specify the _id field using Bulk.IndexMany in ElasticSearch
You can set _id similarly to how you're setting the index name on the BulkDescriptor. Given the following POCO
public class Message{ public string Content { get; set; }}Setting the ids using an incrementing counter for example
var documents = new[] { new Message { Content = "message 1" }, new Message { Content = "another message" }, new Message { Content = "yet another one" }};var indexName = "index-name"; var id = 0;client.Bulk(bd => bd .IndexMany(documents, (descriptor, s) => descriptor.Index(indexName).Id(++id)));yields the following request
POST http://localhost:9200/_bulk{"index":{"_index":"index-name","_type":"message","_id":1}}{"content":"message 1"}{"index":{"_index":"index-name","_type":"message","_id":2}}{"content":"another message"}{"index":{"_index":"index-name","_type":"message","_id":3}}{"content":"yet another one"}