Scoring issue with copy_to

[lucie-wartelle]

Hello !

I'm facing an issue with elasticsearch 8. I have an index that contains companies and I use a copy_to parameters to group searchable fields of these companies. However, some fields can be null, and some can contains strings with spaces. As a result, one company doesn't have the same search field length than another one and it influences search results. For example:

PUT /my-index
{
	mappings: {
		properties: {
			"companyName": {
				"type": "text",
				"store": true,
				"copy_to": "search_field_1"
			},
			"reference": {
				"type": "text",
				"store": true,
				"copy_to": "search_field_1"
			}
			"comment": {
				"type": "text",
				"store": true,
				"copy_to": "search_field_1"
			},
			"otherField": {
				"type": "text",
				"store": true,
				"copy_to": "search_field_2"
			}
		}
	}
}


POST my-index/_doc/
{
	"companyName": "test",
	"reference": "001245",
	"comment": "a large comment",
	"otherField": "00000"
}
POST my-index/_doc/
{
	"companyName": "test company",
	"reference": "123",
	"comment": null,
	"otherField": null
}


GET /_search
{
  "query": {
    "multi_match" : {
      "query": "test", 
      "type": "cross_fields",
      "operator": "and",
      "fields": [ "search_field_1^1", "search_field_2^2" ] 
    }
  }
}

If I search "test", I am expecting the first company as the first result because of its company name. Instead of that, it's the second one, because its search field length is shorter.

Did I miss something here? Should I change my mapping to archive that behavior?