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Elastic Docs ›Elasticsearch Guide [2.4] ›Query DSL ›Term level queries

Exists Query

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Exists Query

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Returns documents that have at least one non-null value in the original field:

{
    "exists" : { "field" : "user" }
}

For instance, these documents would all match the above query:

{ "user": "jane" }
{ "user": "" } 
{ "user": "-" } 
{ "user": ["jane"] }
{ "user": ["jane", null ] }

An empty string is a non-null value.

Even though the standard analyzer would emit zero tokens, the original field is non-null.

At least one non-null value is required.

These documents would not match the above query:

{ "user": null }
{ "user": [] } 
{ "user": [null] } 
{ "foo":  "bar" }

This field has no values.

At least one non-null value is required.

The user field is missing completely.

null_value mapping

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If the field mapping includes the null_value setting then explicit null values are replaced with the specified null_value. For instance, if the user field were mapped as follows:

  "user": {
    "type": "string",
    "null_value": "_null_"
  }

then explicit null values would be indexed as the string _null_, and the following docs would match the exists filter:

{ "user": null }
{ "user": [null] }

However, these docs—​without explicit null values—​would still have no values in the user field and thus would not match the exists filter:

{ "user": [] }
{ "foo": "bar" }

missing query

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The exists query can advantageously replace the missing query when used inside a must_not clause as follows:

"bool": {
    "must_not": {
        "exists": {
            "field": "user"
        }
    }
}

This query returns documents that have no value in the user field.

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