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Exists query
Use the exists
query to search for documents that contain a specific field.
An indexed value will not exist for a document field in any of the following cases:
- The field has
"index" : false
specified in the mapping. - The field in the source JSON is
null
or[]
. - The length of the field value exceeds the
ignore_above
setting in the mapping. - The field value is malformed and
ignore_malformed
is defined in the mapping.
An indexed value will exist for a document field in any of the following cases:
- The value is an array that contains one or more null elements and one or more non-null elements (for example,
["one", null]
). - The value is an empty string (
""
or"-"
). - The value is a custom
null_value
, as defined in the field mapping.
Example
For example, consider an index that contains the following two documents:
PUT testindex/_doc/1
{
"title": "The wind rises"
}
PUT testindex/_doc/2
{
"title": "Gone with the wind",
"description": "A 1939 American epic historical film"
}
The following query searches for documents that contain the description
field:
GET testindex/_search
{
"query": {
"exists": {
"field": "description"
}
}
}
The response contains the matching document:
{
"took": 3,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 1,
"hits": [
{
"_index": "testindex",
"_id": "2",
"_score": 1,
"_source": {
"title": "Gone with the wind",
"description": "A 1939 American epic historical film"
}
}
]
}
}
Finding documents with missing indexed values
To find documents with missing indexed values, you can use the must_not
Boolean query with the inner exists
query. For example, the following request searches for documents in which the description
field is missing:
GET testindex/_search
{
"query": {
"bool": {
"must_not": {
"exists": {
"field": "description"
}
}
}
}
}
The response contains the matching document:
{
"took": 19,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 0,
"hits": [
{
"_index": "testindex",
"_id": "1",
"_score": 0,
"_source": {
"title": "The wind rises"
}
}
]
}
}
Parameters
The query accepts the name of the field (<field>
) as a top-level parameter.
Parameter | Data type | Description |
---|---|---|
boost | Floating-point | A floating-point value that specifies the weight of this field toward the relevance score. Values above 1.0 increase the field’s relevance. Values between 0.0 and 1.0 decrease the field’s relevance. Default is 1.0. |