CODEWITHSUNDEEP
elasticsearch
anks2089
anks2089

Reputation: 57

Elastic search has_child query

We have a parent-child (one to many) relation in elastic search, and we want to check for all parent objects where it's child object attribute(child_attr) has any value in it.

we are generating json-queries as below:

1) For Has value condition.

{
                "has_child" : {
                  "query" : {
                    "filtered" : {
                      "query" : {
                        "match_all" : { }
                      },
                      "filter" : {
                        "and" : {
                          "filters" : [ {
                            "exists" : {
                              "field" : "child_attr"
                            }
                          }, {
                            "not" : {
                              "filter" : {
                                "term" : {
                                  "child_attr" : ""
                                }
                              }
                            }
                          } ]
                        }
                      }
                    }
                  },
                  "type" : "child"
                }
              }

2) For Has No Value Condition

{
                "has_child" : {
                  "query" : {
                    "filtered" : {
                      "query" : {
                        "match_all" : { }
                      },
                      "filter" : {
                        "or" : {
                          "filters" : [ {
                            "missing" : {
                              "field" : "child_attr"
                            }
                          }, {
                            "term" : {
                              "child_attr" : ""
                            }
                          } ]
                        }
                      }
                    }
                  },
                  "type" : "child"
                }
              }

These queries are returning only those parent objects where either all child objects have some value or all child objects have no value the searched attribute.

It doesn't return anything where this condition is met partially which covers majority of data.

I have also toyed with keyword analyzer to index this child_attribute but no joy.

Look forward to your expert suggestions please.

Upvotes: 1

Views: 3806

Answers (1)

imotov
imotov

Reputation: 30163

You are getting unexpected results because the query 

"missing" : {
    "field" : "child_attr"
}

matches both records that were indexed with empty string in the child_attr and records in which child_attr was missing.

The query 

"exists" : {
    "field" : "child_attr"
}

is exact oposite of the first query, it matches all records that were indexed with a non-empty child_attr field.

The query

"term" : {
    "child_attr" : ""
}

doesn't match anything.

Upvotes: 1

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