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* Add has_child query Signed-off-by: Fanit Kolchina <[email protected]> * Rename parameter table header Signed-off-by: Fanit Kolchina <[email protected]> * Update _query-dsl/joining/has-child.md Co-authored-by: Naarcha-AWS <[email protected]> Signed-off-by: kolchfa-aws <[email protected]> * Apply suggestions from code review Co-authored-by: Nathan Bower <[email protected]> Signed-off-by: kolchfa-aws <[email protected]> --------- Signed-off-by: Fanit Kolchina <[email protected]> Signed-off-by: kolchfa-aws <[email protected]> Co-authored-by: Naarcha-AWS <[email protected]> Co-authored-by: Nathan Bower <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,259 @@ | ||
| --- | ||
| layout: default | ||
| title: Has child | ||
| parent: Joining queries | ||
| nav_order: 10 | ||
| --- | ||
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| # Has child query | ||
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| The `has_child` query returns parent documents whose child documents match a specific query. You can establish parent-child relationships between documents in the same index by using a [join]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/join/) field type. | ||
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| The `has_child` query is slower than other queries because of the join operation it performs. Performance decreases as the number of matching child documents pointing to different parent documents increases. Each `has_child` query in your search may significantly impact query performance. If you prioritize speed, avoid using this query or limit its usage as much as possible. | ||
| {: .warning} | ||
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| ## Example | ||
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| Before you can run a `has_child` query, your index must contain a [join]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/join/) field in order to establish parent-child relationships. The index mapping request uses the following format: | ||
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| ```json | ||
| PUT /example_index | ||
| { | ||
| "mappings": { | ||
| "properties": { | ||
| "relationship_field": { | ||
| "type": "join", | ||
| "relations": { | ||
| "parent_doc": "child_doc" | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
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| In this example, you'll configure an index that contains documents representing products and their brands. | ||
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| First, create the index and establish the parent-child relationship between `brand` and `product`: | ||
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| ```json | ||
| PUT testindex1 | ||
| { | ||
| "mappings": { | ||
| "properties": { | ||
| "product_to_brand": { | ||
| "type": "join", | ||
| "relations": { | ||
| "brand": "product" | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
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| Index two parent (brand) documents: | ||
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| ```json | ||
| PUT testindex1/_doc/1 | ||
| { | ||
| "name": "Luxury brand", | ||
| "product_to_brand" : "brand" | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
|
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| ```json | ||
| PUT testindex1/_doc/2 | ||
| { | ||
| "name": "Economy brand", | ||
| "product_to_brand" : "brand" | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
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| Index three child (product) documents: | ||
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| ```json | ||
| PUT testindex1/_doc/3?routing=1 | ||
| { | ||
| "name": "Mechanical watch", | ||
| "sales_count": 150, | ||
| "product_to_brand": { | ||
| "name": "product", | ||
| "parent": "1" | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
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| ```json | ||
| PUT testindex1/_doc/4?routing=2 | ||
| { | ||
| "name": "Electronic watch", | ||
| "sales_count": 300, | ||
| "product_to_brand": { | ||
| "name": "product", | ||
| "parent": "2" | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
|
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| ```json | ||
| PUT testindex1/_doc/5?routing=2 | ||
| { | ||
| "name": "Digital watch", | ||
| "sales_count": 100, | ||
| "product_to_brand": { | ||
| "name": "product", | ||
| "parent": "2" | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
|
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| To search for the parent of a child, use a `has_child` query. The following query returns parent documents (brands) that make watches: | ||
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| ```json | ||
| GET testindex1/_search | ||
| { | ||
| "query" : { | ||
| "has_child": { | ||
| "type":"product", | ||
| "query": { | ||
| "match" : { | ||
| "name": "watch" | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
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| The response returns both brands: | ||
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| ```json | ||
| { | ||
| "took": 15, | ||
| "timed_out": false, | ||
| "_shards": { | ||
| "total": 1, | ||
| "successful": 1, | ||
| "skipped": 0, | ||
| "failed": 0 | ||
| }, | ||
| "hits": { | ||
| "total": { | ||
| "value": 2, | ||
| "relation": "eq" | ||
| }, | ||
| "max_score": 1, | ||
| "hits": [ | ||
| { | ||
| "_index": "testindex1", | ||
| "_id": "1", | ||
| "_score": 1, | ||
| "_source": { | ||
| "name": "Luxury brand", | ||
| "product_to_brand": "brand" | ||
| } | ||
| }, | ||
| { | ||
| "_index": "testindex1", | ||
| "_id": "2", | ||
| "_score": 1, | ||
| "_source": { | ||
| "name": "Economy brand", | ||
| "product_to_brand": "brand" | ||
| } | ||
| } | ||
| ] | ||
| } | ||
| } | ||
| ``` | ||
|
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| ## Parameters | ||
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| The following table lists all top-level parameters supported by `has_child` queries. | ||
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| | Parameter | Required/Optional | Description | | ||
| |:---|:---|:---| | ||
| | `type` | Required | Specifies the name of the child relationship as defined in the `join` field mapping. | | ||
| | `query` | Required | The query to run on child documents. If a child document matches the query, the parent document is returned. | | ||
| | `ignore_unmapped` | Optional | Indicates whether to ignore unmapped `type` fields and not return documents instead of throwing an error. You can provide this parameter when querying multiple indexes, some of which may not contain the `type` field. Default is `false`. | | ||
| | `max_children` | Optional | The maximum number of matching child documents for a parent document. If exceeded, the parent document is excluded from the search results. | | ||
| | `min_children` | Optional | The minimum number of matching child documents required for a parent document to be included in the results. If not met, the parent is excluded. Default is `1`.| | ||
| | `score_mode` | Optional | Defines how scores of matching child documents influence the parent document's score. Valid values are: <br> - `none`: Ignores the relevance scores of child documents and assigns a score of `0` to the parent document. <br> - `avg`: Uses the average relevance score of all matching child documents. <br> - `max`: Assigns the highest relevance score from the matching child documents to the parent. <br> - `min`: Assigns the lowest relevance score from the matching child documents to the parent. <br> - `sum`: Sums the relevance scores of all matching child documents. <br> Default is `none`. | | ||
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| ## Sorting limitations | ||
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| The `has_child` query does not support [sorting results]({{site.url}}{{site.baseurl}}/search-plugins/searching-data/sort/) using standard sorting options. If you need to sort parent documents by fields in their child documents, you can use a [`function_score` query]({{site.url}}{{site.baseurl}}/query-dsl/compound/function-score/) and sort by the parent document's score. | ||
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| In the preceding example, you can sort parent documents (brands) based on the `sales_count` of their child products. This query multiplies the score by the `sales_count` field of the child documents and assigns the highest relevance score from the matching child documents to the parent: | ||
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| ```json | ||
| GET testindex1/_search | ||
| { | ||
| "query": { | ||
| "has_child": { | ||
| "type": "product", | ||
| "query": { | ||
| "function_score": { | ||
| "script_score": { | ||
| "script": "_score * doc['sales_count'].value" | ||
| } | ||
| } | ||
| }, | ||
| "score_mode": "max" | ||
| } | ||
| } | ||
| } | ||
| ``` | ||
| {% include copy-curl.html %} | ||
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| The response contains the brands sorted by the highest child `sales_count`: | ||
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| ```json | ||
| { | ||
| "took": 6, | ||
| "timed_out": false, | ||
| "_shards": { | ||
| "total": 1, | ||
| "successful": 1, | ||
| "skipped": 0, | ||
| "failed": 0 | ||
| }, | ||
| "hits": { | ||
| "total": { | ||
| "value": 2, | ||
| "relation": "eq" | ||
| }, | ||
| "max_score": 300, | ||
| "hits": [ | ||
| { | ||
| "_index": "testindex1", | ||
| "_id": "2", | ||
| "_score": 300, | ||
| "_source": { | ||
| "name": "Economy brand", | ||
| "product_to_brand": "brand" | ||
| } | ||
| }, | ||
| { | ||
| "_index": "testindex1", | ||
| "_id": "1", | ||
| "_score": 150, | ||
| "_source": { | ||
| "name": "Luxury brand", | ||
| "product_to_brand": "brand" | ||
| } | ||
| } | ||
| ] | ||
| } | ||
| } | ||
| ``` |
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