_index field filter performance VS index name in url

Elastic Stack Elasticsearch
1

From performance perspective, does filtering on _index field behave as if i've set the index name in the URL?

    GET log-*/_doc/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "term": {
            "event_name.keyword": {
              "value": "send_email",
              "boost": 1
            }
          }
        },
                {
          "term": {
            "_index": {
              "value": "log-2021-01",
              "boost": 1
            }
          }
        }
      ],
      "boost": 1
    }
  }, "size":10000
}

VS

    GET log-2021-01/_doc/_search
    {
      "query": {
        "bool": {
          "must": [
            {
              "term": {
                "event_name.keyword": {
                  "value": "send_email",
                  "boost": 1
                }
              }
            }
          ],
          "boost": 1
        }
      }
    }
2

Anybody? :slight_smile:

3

I'd prefer the later as elasticsearch will have only one index to visit IMHO.

4

Thanks @dadoonet ! so specifying the term query, like

 "term": {
            "_index": {
              "value": "log-2021-01",
              "boost": 1
            }
          }

does not guarantee that only the specified index will be visited right?
For instance, are such things of how elastic engine work internally documented somewhere? i tried to find the answer before asking, no luck...

5

I think you won't notice a big difference, specifically the second time you run the search as elasticsearch will know that it's useless to visit the index.