Within a sub-aggregation of a reverse_nested aggregation, cannot filter on nested fields

[lmeck]

I'm unsure if this is a bug or something that wasn't intended to work. In the example below, I'm trying to find the 'foo' object that has the nested 'bar' object named 'bar0'. I then want to know how many nested 'baz' objects the 'foo' contains. After using reverse_nested I can use the first-level fields of 'foo0', but not the nested fields.

Using my actual data this sometimes did work, which is why I thought there might be a bug here. So for example two root objects would contain a certain nested object ('bar'), but only one was returning a proper count of another nested object (baz). With my example I wasn't able to recreate this.

DELETE /_all

PUT /foos

PUT /foos/foo/_mapping
{
  "foo": {
    "properties": {
      "bar": {
        "type": "nested",
        "properties": {
          "name": {
            "type": "string"
          }
        }
      },
      "baz": {
        "type": "nested",
        "properties": {
          "name": {
            "type": "string"
          }
        }
      },
      "name": {
        "type": "string"
      }
    }
  }
}

PUT /foos/foo/0
{
  "bar": [
    {
      "name": "bar0"
    },
    {
      "name": "bar1"
    }
  ],
  "baz": [
    {
      "name": "baz0"
    },
    {
      "name": "baz1"
    }
  ],
  "name": "foo0"
}
PUT /foos/foo/1
{
  "bar": [
    {
      "name": "bar2"
    },
    {
      "name": "bar3"
    }
  ],
  "baz": [
    {
      "name": "baz2"
    },
    {
      "name": "baz3"
    }
  ],
  "name": "foo1"
}

#this should give a count of 2 under baz, but it's 0 instead

POST /foos/foo/_search?pretty
{
  "size": 0,
  "aggs": {
    "bar": {
      "nested": {
        "path": "bar"
      },
      "aggs": {
        "bar_filter": {
          "filter": {
            "bool": {
              "must": {
                "term": {
                  "bar.name": "bar0"
                }
              }
            }
          },
          "aggs": {
            "foo": {
              "reverse_nested": {},
              "aggs": {
                "name": {
                  "terms": {
                    "field": "name"
                  },
                  "aggs": {
                    "baz": {
                      "nested": {
                        "path": "baz"
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

# this works and give the right number of baz
POST /foos/foo/_search?pretty
{
  "size": 0,
  "aggs": {
    "foo_filter": {
      "filter": {
        "bool": {
          "must": {
            "term": {
              "name": "foo0"
            }
          }
        }
      },
      "aggs": {
        "baz": {
          "nested": {
            "path": "baz"
          }
        }
      }
    }
  }
}

[clintongormley]

@martijnvg I've confirmed this behaviour - looks like a bug to me.

[martijnvg]

@lmeck @clintongormley This is indeed a bug. I opened #7048 for this.