[BUG] reverse nested context,while shifting from nested to root and root to nested path.

[Shivacharangoud]

Describe the bug

mapping:

PUT reverse_nested
{
    "mappings": {
      "properties": {
        "priority": {
          "type": "long"
        },
        "teams": {
          "type":"nested",
          "properties": {
            "hours": {
              "type": "long"
            },
            "name": {
              "type": "text",
              "fields": {
                "keyword": {
                  "type": "keyword",
                  "ignore_above": 256
                }
              }
            }
          }
        }
      }
    }
  }

**data:**

PUT reverse_nested/_doc/1
{
  "priority":1,
  "teams":[
    {"name":"team1", "hours":10},
    {"name":"team2", "hours":20}
  ]
}

**query:**

GET reverse_nested/_search
{
  "aggs": {
    "group_by_team": {
      "nested": {
        "path": "teams"
      },
      "aggs": {
        "group_by_teamm": {
          "terms": {
            "field": "teams.name.keyword",
            "size": 10
          },
          "aggs": {
            "sum_of_hours": {
              "sum": {
                "field": "teams.hours"
              }
            },
            "reverse_to_base":{
              "reverse_nested": {
              
              },
              "aggs": {
                "group_by_priority": {
                  "terms": {
                    "field": "priority"
                  },
                  "aggs":{
                    "nested_again":{
                      "nested": {
                        "path": "teams"
                      },
                      "aggs": {
                        "sum_of_hours": {
                          "sum": {
                            "field": "teams.hours"
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

**and the response:**
{
  "took": 10,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 1,
      "relation": "eq"
    },
    "max_score": 1,
    "hits": [
      {
        "_index": "reverse_nested",
        "_id": "1",
        "_score": 1,
        "_source": {
          "priority": 1,
          "teams": [
            {
              "name": "team1",
              "hours": 10
            },
            {
              "name": "team2",
              "hours": 20
            }
          ]
        }
      }
    ]
  },
  "aggregations": {
    "group_by_team": {
      "doc_count": 2,
      "group_by_teamm": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [
          {
            "key": "team1",
            "doc_count": 1,
            "reverse_to_base": {
              "doc_count": 1,
              "group_by_priority": {
                "doc_count_error_upper_bound": 0,
                "sum_other_doc_count": 0,
                "buckets": [
                  {
                    "key": 1,
                    "doc_count": 1,
                    "nested_again": {
                      "doc_count": 2,
                      "sum_of_hours": {
                        "value": 30
                      }
                    }
                  }
                ]
              }
            },
            "sum_of_hours": {
              "value": 10
            }
          },
          {
            "key": "team2",
            "doc_count": 1,
            "reverse_to_base": {
              "doc_count": 1,
              "group_by_priority": {
                "doc_count_error_upper_bound": 0,
                "sum_other_doc_count": 0,
                "buckets": [
                  {
                    "key": 1,
                    "doc_count": 1,
                    "nested_again": {
                      "doc_count": 2,
                      "sum_of_hours": {
                        "value": 30
                      }
                    }
                  }
                ]
              }
            },
            "sum_of_hours": {
              "value": 20
            }
          }
        ]
      }
    }
  }
}

Let's try to produce a report that gives number of hours by team by priority. Doing nested aggregation on teams.name and then reverse nested to group on priority and then nested to sum teams.hours double-counts hours because second nesting on teams knows nothing about upstream nesting as it is executed in context of request and as result it will lump hours for each team on request under the top level team aggregation. sum of hour under team is 10 and 20 but when we group again with priority( under each team ) and perform sum of hour its 30 means its considering two nested team objects. how to solve this issue?

Related component

Search:Aggregations

To Reproduce

mapping:

PUT reverse_nested
{
    "mappings": {
      "properties": {
        "priority": {
          "type": "long"
        },
        "teams": {
          "type":"nested",
          "properties": {
            "hours": {
              "type": "long"
            },
            "name": {
              "type": "text",
              "fields": {
                "keyword": {
                  "type": "keyword",
                  "ignore_above": 256
                }
              }
            }
          }
        }
      }
    }
  }

**data:**

PUT reverse_nested/_doc/1
{
  "priority":1,
  "teams":[
    {"name":"team1", "hours":10},
    {"name":"team2", "hours":20}
  ]
}

**query:**

GET reverse_nested/_search
{
  "aggs": {
    "group_by_team": {
      "nested": {
        "path": "teams"
      },
      "aggs": {
        "group_by_teamm": {
          "terms": {
            "field": "teams.name.keyword",
            "size": 10
          },
          "aggs": {
            "sum_of_hours": {
              "sum": {
                "field": "teams.hours"
              }
            },
            "reverse_to_base":{
              "reverse_nested": {
              
              },
              "aggs": {
                "group_by_priority": {
                  "terms": {
                    "field": "priority"
                  },
                  "aggs":{
                    "nested_again":{
                      "nested": {
                        "path": "teams"
                      },
                      "aggs": {
                        "sum_of_hours": {
                          "sum": {
                            "field": "teams.hours"
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

Expected behavior

expected result:

{
  "took": 10,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": {
      "value": 1,
      "relation": "eq"
    },
    "max_score": 1,
    "hits": [
      {
        "_index": "reverse_nested",
        "_id": "1",
        "_score": 1,
        "_source": {
          "priority": 1,
          "teams": [
            {
              "name": "team1",
              "hours": 10
            },
            {
              "name": "team2",
              "hours": 20
            }
          ]
        }
      }
    ]
  },
  "aggregations": {
    "group_by_team": {
      "doc_count": 2,
      "group_by_teamm": {
        "doc_count_error_upper_bound": 0,
        "sum_other_doc_count": 0,
        "buckets": [
          {
            "key": "team1",
            "doc_count": 1,
            "reverse_to_base": {
              "doc_count": 1,
              "group_by_priority": {
                "doc_count_error_upper_bound": 0,
                "sum_other_doc_count": 0,
                "buckets": [
                  {
                    "key": 1,
                    "doc_count": 1,
                    "nested_again": {
                      "doc_count": 2,
                      "sum_of_hours": {
                        "value": 10
                      }
                    }
                  }
                ]
              }
            },
            "sum_of_hours": {
              "value": 10
            }
          },
          {
            "key": "team2",
            "doc_count": 1,
            "reverse_to_base": {
              "doc_count": 1,
              "group_by_priority": {
                "doc_count_error_upper_bound": 0,
                "sum_other_doc_count": 0,
                "buckets": [
                  {
                    "key": 1,
                    "doc_count": 1,
                    "nested_again": {
                      "doc_count": 2,
                      "sum_of_hours": {
                        "value": 20
                      }
                    }
                  }
                ]
              }
            },
            "sum_of_hours": {
              "value": 20
            }
          }
        ]
      }
    }
  }
}

Additional Details

• OS: aws mananged opensearch service.
• Version : 2.1