Add script score query (#4970)

* Add script score query

Signed-off-by: Fanit Kolchina <kolchfa@amazon.com>

* Add copy buttons

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* Add note about expensive queries

Signed-off-by: Fanit Kolchina <kolchfa@amazon.com>

* Implemented tech review comments

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* Rewording

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* Rewording

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* Apply suggestions from code review

Co-authored-by: Melissa Vagi <vagimeli@amazon.com>
Signed-off-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _query-dsl/specialized/script-score.md

Co-authored-by: Melissa Vagi <vagimeli@amazon.com>
Signed-off-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Nathan Bower <nbower@amazon.com>
Signed-off-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* More editorial comments and field name change

Signed-off-by: Fanit Kolchina <kolchfa@amazon.com>

---------

Signed-off-by: Fanit Kolchina <kolchfa@amazon.com>
Signed-off-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>
Co-authored-by: Melissa Vagi <vagimeli@amazon.com>
Co-authored-by: Nathan Bower <nbower@amazon.com>
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@ -37,17 +37,17 @@ Broadly, you can classify queries into two categories---*leaf queries* and *comp
- **Leaf queries**: Leaf queries search for a specified value in a certain field or fields. You can use leaf queries on their own. They include the following query types:
- **Full-text queries**: Use full-text queries to search text documents. For an analyzed text field search, full-text queries split the query string into terms using the same analyzer that was used when the field was indexed. For an exact value search, full-text queries look for the specified value without applying text analysis. To learn more, see [Full-text queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/full-text/index/).
- [Full-text queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/full-text/index/): Use full-text queries to search text documents. For an analyzed text field search, full-text queries split the query string into terms using the same analyzer that was used when the field was indexed. For an exact value search, full-text queries look for the specified value without applying text analysis.
- **Term-level queries**: Use term-level queries to search documents for an exact term, such as an ID or value range. Term-level queries do not analyze search terms or sort results by relevance score. To learn more, see [Term-level queries]({{site.url}}{{site.baseurl}}/query-dsl/term/index/).
- [Term-level queries]({{site.url}}{{site.baseurl}}/query-dsl/term/index/): Use term-level queries to search documents for an exact term, such as an ID or value range. Term-level queries do not analyze search terms or sort results by relevance score.
- **Geographic and xy queries**: Use geographic queries to search documents that include geographic data. Use xy queries to search documents that include points and shapes in a two-dimensional coordinate system. To learn more, see [Geographic and xy queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/geo-and-xy/index).
- [Geographic and xy queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/geo-and-xy/index/): Use geographic queries to search documents that include geographic data. Use xy queries to search documents that include points and shapes in a two-dimensional coordinate system.
- **Joining queries**: Use joining queries to search nested fields or return parent and child documents that match a specific query. Types of joining queries include `nested`, `has_child`, `has_parent`, and `parent_id` queries.
- Joining queries: Use joining queries to search nested fields or return parent and child documents that match a specific query. Types of joining queries include `nested`, `has_child`, `has_parent`, and `parent_id` queries.
- **Span queries**: Use span queries to perform precise positional searches. Span queries are low-level, specific queries that provide control over the order and proximity of specified query terms. They are primarily used to search legal documents. To learn more, see [Span queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/span-query/).
- [Span queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/span-query/): Use span queries to perform precise positional searches. Span queries are low-level, specific queries that provide control over the order and proximity of specified query terms. They are primarily used to search legal documents.
- **Specialized queries**: Specialized queries include all other query types (`distance_feature`, `more_like_this`, `percolate`, `rank_feature`, `script`, `script_score`, `wrapper`, and `pinned_query`).
- [Specialized queries]({{site.url}}{{site.baseurl}}/query-dsl/specialized/index/): Specialized queries include all other query types (`distance_feature`, `more_like_this`, `percolate`, `rank_feature`, `script`, `script_score`, and `wrapper`).
- **Compound queries**: Compound queries serve as wrappers for multiple leaf or compound clauses, either to combine their results or to modify their behavior. They include the Boolean, disjunction max, constant score, function score, and boosting query types. To learn more, see [Compound queries]({{site.url}}{{site.baseurl}}/opensearch/query-dsl/compound/index/).

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@ -0,0 +1,25 @@
---
layout: default
title: Specialized queries
has_children: true
nav_order: 65
has_toc: false
---
# Specialized queries
OpenSearch supports the following specialized queries:
- `distance_feature`: Calculates document scores based on the dynamically calculated distance between the origin and a document's `date`, `date_nanos`, or `geo_point` fields. This query can skip non-competitive hits.
- `more_like_this`: Finds documents similar to the provided text, document, or collection of documents.
- `percolate`: Finds queries (stored as documents) that match the provided document.
- `rank_feature`: Calculates scores based on the values of numeric features. This query can skip non-competitive hits.
- `script`: Uses a script as a filter.
- `script_score`: Calculates a custom score for matching documents using a script.
- `wrapper`: Accepts other queries as JSON or YAML strings.

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@ -0,0 +1,332 @@
---
layout: default
title: Script score
parent: Specialized queries
grand_parent: Query DSL
nav_order: 60
---
# Script score query
Use a `script_score` query to customize the score calculation by using a script. For an expensive scoring function, you can use a `script_score` query to calculate the score only for the returned documents that have been filtered.
## Example
For example, the following request creates an index containing one document:
```json
PUT testindex1/_doc/1
{
"name": "John Doe",
"multiplier": 0.5
}
```
{% include copy-curl.html %}
You can use a `match` query to return all documents that contain `John` in the `name` field:
```json
GET testindex1/_search
{
"query": {
"match": {
"name": "John"
}
}
}
```
{% include copy-curl.html %}
In the response, document 1 has a score of `0.2876821`:
```json
{
"took": 7,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 0.2876821,
"hits": [
{
"_index": "testindex1",
"_id": "1",
"_score": 0.2876821,
"_source": {
"name": "John Doe",
"multiplier": 0.5
}
}
]
}
}
```
Now let's change the document score by using a script that calculates the score as the value of the `_score` field multiplied by the value of the `multiplier` field. In the following query, you can access the current relevance score of a document in the `_score` variable and the `multiplier` value as `doc['multiplier'].value`:
```json
GET testindex1/_search
{
"query": {
"script_score": {
"query": {
"match": {
"name": "John"
}
},
"script": {
"source": "_score * doc['multiplier'].value"
}
}
}
}
```
{% include copy-curl.html %}
In the response, the score for document 1 is half of the original score:
```json
{
"took": 8,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"skipped": 0,
"failed": 0
},
"hits": {
"total": {
"value": 1,
"relation": "eq"
},
"max_score": 0.14384104,
"hits": [
{
"_index": "testindex1",
"_id": "1",
"_score": 0.14384104,
"_source": {
"name": "John Doe",
"multiplier": 0.5
}
}
]
}
}
```
## Parameters
The `script_score` query supports the following top-level parameters.
Parameter | Data type | Description
:--- | :--- | :---
`query` | Object | The query used for search. Required.
`script` | Object | The script used to calculate the score of the documents returned by the `query`. Required.
`min_score` | Float | Excludes documents with a score lower than `min_score` from the results. Optional.
`boost` | Float | Boosts the documents' scores by the given multiplier. Values less than 1.0 decrease relevance, and values greater than 1.0 increase relevance. Default is 1.0.
The relevance scores calculated by the `script_score` query cannot be negative.
{: .important}
## Customizing score calculation with built-in functions
To customize score calculation, you can use one of the built-in Painless functions. For every function, OpenSearch provides one or more Painless methods you can access in the script score context. You can call the Painless methods listed in the following sections directly without using a class name or instance name qualifier.
### Saturation
The saturation function calculates saturation as `score = value /(value + pivot)`, where `value` is the field value and `pivot` is chosen so that the score is greater than 0.5 if `value` is greater than `pivot` and less than 0.5 if `value` is less than `pivot`. The score is in the (0, 1) range. To apply a saturation function, call the following Painless method:
- `double saturation(double <field-value>, double <pivot>)`
#### Example
The following example query searches for the text `neural search` in the `articles` index. It combines the original document relevance score with the `article_rank` value, which is first transformed with a saturation function:
```json
GET articles/_search
{
"query": {
"script_score": {
"query": {
"match": { "article_name": "neural search" }
},
"script" : {
"source" : "_score + saturation(doc['article_rank'].value, 11)"
}
}
}
}
```
{% include copy-curl.html %}
### Sigmoid
Similarly to the saturation function, the sigmoid function calculates the score as `score = value^exp/ (value^exp + pivot^exp)`, where `value` is the field value, `exp` is an exponent scaling factor, and `pivot` is chosen so that the score is greater than 0.5 if `value` is greater than `pivot` and less than 0.5 if `value` is less than `pivot`. To apply a sigmoid function, call the following Painless method:
- `double sigmoid(double <field-value>, double <pivot>, double <exp>)`
#### Example
The following example query searches for the text `neural search` in the `articles` index. It combines the original document relevance score with the `article_rank` value, which is first transformed with a sigmoid function:
```json
GET articles/_search
{
"query": {
"script_score": {
"query": {
"match": { "article_name": "neural search" }
},
"script" : {
"source" : "_score + sigmoid(doc['article_rank'].value, 11, 2)"
}
}
}
}
```
{% include copy-curl.html %}
### Random score
The random score function generates uniformly distributed random scores in the [0, 1) range. To learn how the function works, see [The random score function]({{site.url}}{{site.baseurl}}/query-dsl/compound/function-score#the-random-score-function). To apply a random score function, call one of the following Painless methods:
- `double randomScore(int <seed>)`: Uses the internal Lucene document IDs as seed values.
- `double randomScore(int <seed>, String <field-name>)`
#### Example
The following query uses the `random_score` function with a `seed` and a `field`:
```json
GET articles/_search
{
"query": {
"script_score": {
"query": {
"match": { "article_name": "neural search" }
},
"script" : {
"source" : "randomScore(20, '_seq_no')"
}
}
}
}
```
{% include copy-curl.html %}
### Decay functions
With decay functions, you can score results based on proximity or recency. To learn more, see [Decay functions]({{site.url}}{{site.baseurl}}/query-dsl/compound/function-score#decay-functions). You can calculate scores using an exponential, Gaussian, or linear decay curve. To apply a decay function, call one of the following Painless methods, depending on the field type:
- [Numeric]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/numeric/) fields:
- `double decayNumericGauss(double <origin>, double <scale>, double <offset>, double <decay>, double <field-value>)`
- `double decayNumericExp(double <origin>, double <scale>, double <offset>, double <decay>, double <field-value>)`
- `double decayNumericLinear(double <origin>, double <scale>, double <offset>, double <decay>, double <field-value>)`
- [Geopoint]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/geo-point/) fields:
- `double decayGeoGauss(String <origin>, String <scale>, String <offset>, double <decay>, GeoPoint <field-value>)`
- `double decayGeoExp(String <origin>, String <scale>, String <offset>, double <decay>, GeoPoint <field-value>)`
- `double decayGeoLinear(String <origin>, String <scale>, String <offset>, double <decay>, GeoPoint <field-value>)`
- [Date]({{site.url}}{{site.baseurl}}/field-types/supported-field-types/date/) fields:
- `double decayDateGauss(String <origin>, String <scale>, String <offset>, double <decay>, JodaCompatibleZonedDateTime <field-value>)`
- `double decayDateExp(String <origin>, String <scale>, String <offset>, double <decay>, JodaCompatibleZonedDateTime <field-value>)`
- `double decayDateLinear(String <origin>, String <scale>, String <offset>, double <decay>, JodaCompatibleZonedDateTime <field-value>)`
#### Example: Numeric fields
The following query uses the exponential decay function on a numeric field:
```json
GET articles/_search
{
"query": {
"script_score": {
"query": {
"match": {
"article_name": "neural search"
}
},
"script": {
"source": "decayNumericExp(params.origin, params.scale, params.offset, params.decay, doc['article_rank'].value)",
"params": {
"origin": 50,
"scale": 20,
"offset": 30,
"decay": 0.5
}
}
}
}
}
```
{% include copy-curl.html %}
#### Example: Geopoint fields
The following query uses the Gaussian decay function on a geopoint field:
```json
GET hotels/_search
{
"query": {
"script_score": {
"query": {
"match": {
"name": "hotel"
}
},
"script": {
"source": "decayGeoGauss(params.origin, params.scale, params.offset, params.decay, doc['location'].value)",
"params": {
"origin": "40.71,74.00",
"scale": "300ft",
"offset": "200ft",
"decay": 0.25
}
}
}
}
}
```
{% include copy-curl.html %}
#### Example: Date fields
The following query uses the linear decay function on a date field:
```json
GET blogs/_search
{
"query": {
"script_score": {
"query": {
"match": {
"name": "opensearch"
}
},
"script": {
"source": "decayDateLinear(params.origin, params.scale, params.offset, params.decay, doc['date_posted'].value)",
"params": {
"origin": "2022-04-24",
"scale": "6d",
"offset": "1d",
"decay": 0.25
}
}
}
}
}
```
{% include copy-curl.html %}
If [`search.allow_expensive_queries`]({{site.url}}{{site.baseurl}}/query-dsl/index/#expensive-queries) is set to `false`, `script_score` queries are not executed.
{: .important}