Aggregate + sort + paginate on nested documents

[t0mer (Tomer)]

Hi,
I'm managing a product index, with product sales and other KPIs under a nested field.
Trying to sort based on nested aggregation, and paginate - with no success.
Below is a simplified version of my mapping, for the sake of the example -

{
                "product_type":
                {
                    "type": "keyword"
                },
                "family":
                {
                    "type": "keyword"
                },
                "rootdomain":
                {
                    "type": "keyword"
                },
                "kpis":
                {
                    "type": "nested",
                    "properties":
                    {
                        "sales_1d":
                        {
                            "type": "float"
                        },
                        "timestamp":
                        {
                            "type": "date",
                            "format": "strict_date_optional_time_nanos"
                        },
                        "views_1d":
                        {
                            "type": "float"
                        }
                    }
                }
            }

My aggregation is similar to the one below-

{
  "aggs": {
    "group_by_family": {
      "aggs": {
        "nested_aggregation": {
          "aggs": {
            "range_filtered": {
              "aggs": {
                "sales_1d": {
                  "sum": {
                    "field": "kpis.sales_1d"
                  }
                },
                "views_1d": {
                  "sum": {
                    "field": "kpis.views_1d"
                  }
                },
                "reverse_nesting": {
                  "aggs": {
                    "docs": {
                      "top_hits": {
                        "size": 1,
                        "sort": [
                          {
                            "_id": {
                              "order": "asc"
                            }
                          }
                        ],
                        "_source": {
                          "includes": [
                            "_id",
                            "family",
                            "rootdomain",
                            "product_type"
                          ]
                        }
                      }
                    }
                  },
                  "reverse_nested": {}
                }
              },
              "filter": {
                "range": {
                  "kpis.timestamp": {
                    "format": "basic_date_time_no_millis",
                    "gte": "20220721T000000Z",
                    "lte": "20220918T235959Z"
                  }
                }
              }
            }
          },
          "nested": {
            "path": "kpis"
          }
        }
      },
      "terms": {
        "field": "family",
        "size": 10
      }
    }
  },
  "query": {
  //some query to filter by product-type and rootdomain  
},
  "size": 0
}

I'm aware that I can add an order clause to term aggregation to order the aggregated results.
My target though is to paginate the aggregated results - meaning I want to retrieve and order
1-10 best-selling products, and later retrieve 11-20 best-selling products and so on.
I've tried using bucket sort under range_filtered but I'm getting an error -

class org.elasticsearch.search.aggregations.bucket.filter.InternalFilter cannot be cast to class org.elasticsearch.search.aggregations.InternalMultiBucketAggregation

I'm not sure how to proceed from here, is this possible? if not, is there any workaround?

Thanks.

[t0mer (Tomer)]

Any help?