Learning Elasticsearch

Copying only missing documents

You can copy only missing documents from one index to another by setting the op_type to create. Any existing documents with the same identifier will get a conflict. By setting conflicts to proceed in the request, reindex will ignore the existing documents, as shown next:

POST _reindex {   "conflicts": "proceed",   "source": {     "index": "source_index"   },   "dest": {     "index": "dest_index",     "op_type": "create"   } }