149 lines
3.0 KiB
Markdown
149 lines
3.0 KiB
Markdown
---
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layout: default
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title: Exists
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parent: Term-level queries
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grand_parent: Query DSL
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nav_order: 10
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---
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# Exists query
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Use the `exists` query to search for documents that contain a specific field.
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An indexed value will not exist for a document field in any of the following cases:
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- The field has `"index" : false` specified in the mapping.
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- The field in the source JSON is `null` or `[]`.
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- The length of the field value exceeds the `ignore_above` setting in the mapping.
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- The field value is malformed and `ignore_malformed` is defined in the mapping.
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An indexed value will exist for a document field in any of the following cases:
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- The value is an array that contains one or more null elements and one or more non-null elements (for example, `["one", null]`).
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- The value is an empty string (`""` or `"-"`).
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- The value is a custom `null_value`, as defined in the field mapping.
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## Example
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For example, consider an index that contains the following two documents:
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```json
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PUT testindex/_doc/1
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{
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"title": "The wind rises"
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}
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```
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{% include copy-curl.html %}
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```json
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PUT testindex/_doc/2
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{
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"title": "Gone with the wind",
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"description": "A 1939 American epic historical film"
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}
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```
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{% include copy-curl.html %}
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The following query searches for documents that contain the `description` field:
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```json
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GET testindex/_search
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{
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"query": {
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"exists": {
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"field": "description"
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}
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}
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}
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```
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{% include copy-curl.html %}
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The response contains the matching document:
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```json
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{
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"took": 3,
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"timed_out": false,
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"_shards": {
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"total": 1,
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"successful": 1,
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"skipped": 0,
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"failed": 0
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},
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"hits": {
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"total": {
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"value": 1,
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"relation": "eq"
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},
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"max_score": 1,
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"hits": [
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{
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"_index": "testindex",
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"_id": "2",
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"_score": 1,
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"_source": {
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"title": "Gone with the wind",
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"description": "A 1939 American epic historical film"
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}
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}
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]
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}
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}
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```
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## Finding documents with missing indexed values
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To find documents with missing indexed values, you can use the `must_not` [Boolean query]({{site.url}}{{site.baseurl}}/query-dsl/compound/bool/) with the inner `exists` query. For example, the following request searches for documents in which the `description` field is missing:
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```json
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GET testindex/_search
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{
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"query": {
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"bool": {
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"must_not": {
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"exists": {
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"field": "description"
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}
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}
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}
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}
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}
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```
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{% include copy-curl.html %}
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The response contains the matching document:
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```json
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{
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"took": 19,
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"timed_out": false,
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"_shards": {
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"total": 1,
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"successful": 1,
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"skipped": 0,
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"failed": 0
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},
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"hits": {
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"total": {
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"value": 1,
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"relation": "eq"
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},
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"max_score": 0,
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"hits": [
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{
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"_index": "testindex",
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"_id": "1",
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"_score": 0,
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"_source": {
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"title": "The wind rises"
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}
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}
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]
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}
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}
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```
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## Parameters
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The query accepts the name of the field (`<field>`) as a top-level parameter. |