Calculated positional field based on _score

[jcater (Jason Cater)]

I need to add a position/ordinal field to my Elasticsearch search results, relative to a sort by _score, regardless of how the actual results are sorted. I'm using the term "field" loosely... I just need access to some ordinal number.

Currently, I only sort my documents by _score. So, I can just calculate this position/ordinal in the calling code. (i.e., the first result is always position #1, the second is #2, the nth is #n, etc.) This is as straight-forward as you can get:

  Position, First, Last, City, State (Score)
  1, John, Smith, Memphis, TN  (_score: 0.9)
  2, Jane, Doe, Atlanta, GA  (_score: 0.8)
  3, James, Wilson, San Francisco, CA  (_score: 0.6)
  4, Jeff, Smith, Dallas, TX  (_score: 0.5)
  5, Kevin, Richards, Austin, TX  (_score: 0.4)

However, I now have the need to sort by other fields, but I still need to know the relative position based on sorting by _score. For example, if I sort by City in the above example, I still need the Position calculated as if we're sorting by score:

Position, First, Last, City, State (Score) 
2, Jane, Doe, Atlanta, GA (_score: 0.8) 
5, Kevin, Richards, Austin, TX (_score: 0.4) 
4, Jeff, Smith, Dallas, TX (_score: 0.5) 
1, John, Smith, Memphis, TN (_score: 0.9) 
3, James, Wilson, San Francisco, CA (_score: 0.6)

To do this without pulling all results from Elasticsearch and doing my own sorting in the calling code (which isn't feasible), I need to shift the calculation of this value to Elasticsearch somehow.

Is there a mechanism to do this in Elasticsearch that I'm overlooking?

[mayya (Mayya Sharipova)]

I can't think of any easy way to do that. One thing you can do is to use 1/score as a proxy for your position, and add to your sort criteria, a sort like this:

  "sort": {
    "_script": {
      "type": "number",
      "script": {
        "lang": "painless",
        "source": "1/_score"
      },
      "order": "desc"
    }
  }