Question

I have mapped an associated field as a multi-field. I have set the ‘name’ property to be analyzed using a snow ball analyzer and ‘exact’ as not analyzed. I am able to search on this field and filter as well. I am not able to sort on this field. When trying to sort, elastic returns an error “Can’t sort on string types with more than one value per doc, or more than one token per field”.

I have attempted creating an additional field called ‘raw’ similar to exact, and this did not work either. Below is my mapping and how I am attempting to perform the sort via the tire gem:

    mapping do
    indexes :sectors, :type => 'object',
      :properties => { :name => { :type => 'multi_field',
                                  :fields => {
                                    :name =>  { :type => 'string', :analyzer => 'snowball' },
                                    :exact => { :type => 'string', :index => 'not_analyzed' , :include_in_all => false }
                                  }
                                  }
                       }
end

def to_indexed_json
    to_json( :include => {
               ...
               :sectors => { :only => ["name"] },
               ...
    })
end

def self.search(params)
  tire.search(:load => true, :page=>params[:page], :per_page => 12) do

    if params[:query].present?
      query { string params[:query], :default_operator => "OR" }
    else
      query { all }
    end

    filter :term, "sectors.name.exact" => params[:sector] if params[:sector].present?
    sort { by 'sectors.name.exact','asc' } if !params[:sort][:sector].blank?
  end
end

Answer 1

There are basically two reasons why you’re getting that error:

• You have more than one value per field: your field is analyzed and the tokenizer produces multiple tokens out of its content, which is not the case with your name.exact field since it’s not_analyzed in your mapping
• You have more than one value per document: you’re adding multiple values to the name field, for example providing an array of values while indexing.

I would check what your documents look like. In order to do it quickly you can make a Terms Facet based on a script which returns the number of items included in the name.exact field like the following. If you get back at least one of the facet entries with term greather than 1, it means that you’ve added multiple values to the field at least once, thus you cannot sort on it.

{
    "query" : {
        "match_all" : {}
    },
    "facets" : {
        "my_facet" : {
            "terms" : {
                "script_field" : "doc['name.exact'].values.length"
            }
        }
    }
}