How to filter aggregation in elasticsearch?

Question

elasticsearch

I am doing this aggregation:

{
"aggs": {
    "characteristics": {
        "terms": {
            "field": "product_char.char_id"
        },
        "aggs": {
            "value": {
                "terms": {
                    "field": "product_char.value.keyword"
                }
            }
        }
    }
}
}

And I want to get the unique value of a particular characteristic, but instead in value I get all possible values ​​​​of all characteristics combined. How to make it so that each unique characteristics has its own set of unique values