elasticsearch sort by score - same field searchable but score different?

Question

I'm trying to sort my ES results by 2 fields: searchable and year.

The mapping in my Rails app:

# mapping
  def as_indexed_json(options={}) 
    as_json(only: [:id, :searchable, :year]) 
  end 

  settings index: { number_of_shards: 5, number_of_replicas: 1 } do
    mapping do
      indexes :id, index: :not_analyzed
      indexes :searchable
      indexes :year
    end
  end

The query:

 @records = Wine.search(query: {match: {searchable: {query:params[:search], fuzziness:2, prefix_length:1}}}, sort: {_score: {order: :desc}, year: {order: :desc}}, size:100)

The interesting thing in the query:

sort: {_score: {order: :desc}, year: {order: :desc}}

I think the query is working well with the 2 sort params. My problem is the score is not the same for 2 documents with the same name (searchable field).

For example, I'm searching for "winery":

You can see a very different score, even if the searchable field is the same. I think the issue is due to the ID field (it's an UUID in fact). Looks like this ID field influences the score. But in my schema mapping, I wrote that ID should not be analyzed and in my ES query, I ask to search ONLY in "searchable" field, not in ID too.

What did I miss to math the same score for same fields ? (actually, sorting by year after score is not useful cos' scores are different for same fields)

Answer 1

Scores are different, because they are calculated independently for each shard. See here for more info.