Query Execution order?

Elastic Stack Elasticsearch
1

Hi,

I have query like this:

POST data-*/_search
{  "_source":  [ "Date","Source", "Name","company" ],
"query": {
    "nested": {
      "path": "List",
      "inner_hits": {
       "_source": [
          "university","Name","Code","State","Status","Articles","PIN"
        ]  
      },
"query": {
    "bool": { 
      "must": {
        "term": { "List.PIN":{"value":149}}
      },
      "filter": {
        "terms":{"List.Code":[276,915,319]} }
}
}
}
}
}

I have data-* indices which contain 1000 documents . I want to know whether _source will work first or after bool query. Why because if _source worked first then it will take 1000 documents content and then remove as per bool query which will take time. Or it will run _source after bool query so that it have to take 3 doc's since List.Code has 3 id's

Thanks

2

The inner_hits part is executed after the search during the fetch phase so the _source is retrieved only for the top hits that match the query.

3

Thanks @jimczi

SO, you are saying _source will only apply on the hits of bool query. Right?

Correct me if i am wrong

Thanks

4

Sort of yes since inner_hits is applied to each top hits returned in the response. If your search matches 1M documents, it will be applied to the 10 best document returned by the query.