Score index

Hi all ,

I have a question related to a specefic index that contains documents like the following :

  "_shard": 0,
  "_node": "Ck_a7Bg2Q4uHjQU82Sfpqg",
  "_index": "indexname",
  "_type": "message",
  "_id": "AVHTfTrYxuJAhPSBWMaa",
  "_score": 1,
  "sort": [
  "_explanation": {
    "value": 1,
    "description": "ConstantScore(*:*), product of:",
    "details": [
        "value": 1,
        "description": "boost"
        "value": 1,
        "description": "queryNorm"

I vaguely understood that is the for optimize the serch operations
I can not see how this index is created and what is exactly the purpose of it .

Any help will be apreciate it .

Thanks .

Can you share the query you sent to produce this? The explanation structure may depend on the query itself.