304 lines
9.5 KiB
Plaintext
304 lines
9.5 KiB
Plaintext
[[query-dsl-script-score-query]]
|
|
=== Script Score Query
|
|
|
|
experimental[]
|
|
|
|
The `script_score` allows you to modify the score of documents that are
|
|
retrieved by a query. This can be useful if, for example, a score
|
|
function is computationally expensive and it is sufficient to compute
|
|
the score on a filtered set of documents.
|
|
|
|
To use `script_score`, you have to define a query and a script -
|
|
a function to be used to compute a new score for each document returned
|
|
by the query. For more information on scripting see
|
|
<<modules-scripting, scripting documentation>>.
|
|
|
|
|
|
Here is an example of using `script_score` to assign each matched document
|
|
a score equal to the number of likes divided by 10:
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
GET /_search
|
|
{
|
|
"query" : {
|
|
"script_score" : {
|
|
"query" : {
|
|
"match": { "message": "elasticsearch" }
|
|
},
|
|
"script" : {
|
|
"source" : "doc['likes'].value / 10 "
|
|
}
|
|
}
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// CONSOLE
|
|
// TEST[setup:twitter]
|
|
|
|
==== Accessing the score of a document within a script
|
|
|
|
Within a script, you can
|
|
{ref}/modules-scripting-fields.html#scripting-score[access]
|
|
the `_score` variable which represents the current relevance score of a
|
|
document.
|
|
|
|
|
|
==== Predefined functions within a Painless script
|
|
You can use any of the available
|
|
<<painless-api-reference, painless functions>> in the painless script.
|
|
Besides these functions, there are a number of predefined functions
|
|
that can help you with scoring. We suggest you to use them instead of
|
|
rewriting equivalent functions of your own, as these functions try
|
|
to be the most efficient by using the internal mechanisms.
|
|
|
|
===== rational
|
|
`rational(value,k) = value/(k + value)`
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "rational(doc['likes'].value, 1)"
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
===== sigmoid
|
|
`sigmoid(value, k, a) = value^a/ (k^a + value^a)`
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "sigmoid(doc['likes'].value, 2, 1)"
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
|
|
[[random-functions]]
|
|
===== Random functions
|
|
There are two predefined ways to produce random values:
|
|
|
|
1. `randomNotReproducible()` uses `java.util.Random` class
|
|
to generate a random value of the type `long`.
|
|
The generated values are not reproducible between requests' invocations.
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "randomNotReproducible()"
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
|
|
2. `randomReproducible(String seedValue, int seed)` produces
|
|
reproducible random values of type `long`. This function requires
|
|
more computational time and memory than the non-reproducible version.
|
|
|
|
A good candidate for the `seedValue` is document field values that
|
|
are unique across documents and already pre-calculated and preloaded
|
|
in the memory. For example, values of the document's `_seq_no` field
|
|
is a good candidate, as documents on the same shard have unique values
|
|
for the `_seq_no` field.
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "randomReproducible(Long.toString(doc['_seq_no'].value), 100)"
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
|
|
A drawback of using `_seq_no` is that generated values change if
|
|
documents are updated. Another drawback is not absolute uniqueness, as
|
|
documents from different shards with the same sequence numbers
|
|
generate the same random values.
|
|
|
|
If you need random values to be distinct across different shards,
|
|
you can use a field with unique values across shards,
|
|
such as `_id`, but watch out for the memory usage as all
|
|
these unique values need to be loaded into memory.
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "randomReproducible(doc['_id'].value, 100)"
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
|
|
[[decay-functions]]
|
|
===== Decay functions for numeric fields
|
|
You can read more about decay functions
|
|
{ref}/query-dsl-function-score-query.html#function-decay[here].
|
|
|
|
* `double decayNumericLinear(double origin, double scale, double offset, double decay, double docValue)`
|
|
* `double decayNumericExp(double origin, double scale, double offset, double decay, double docValue)`
|
|
* `double decayNumericGauss(double origin, double scale, double offset, double decay, double docValue)`
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "decayNumericLinear(params.origin, params.scale, params.offset, params.decay, doc['dval'].value)",
|
|
"params": { <1>
|
|
"origin": 20,
|
|
"scale": 10,
|
|
"decay" : 0.5,
|
|
"offset" : 0
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
<1> Use `params` to compile a script only once for different values of parameters
|
|
|
|
|
|
===== Decay functions for geo fields
|
|
|
|
* `double decayGeoLinear(String originStr, String scaleStr, String offsetStr, double decay, GeoPoint docValue)`
|
|
|
|
* `double decayGeoExp(String originStr, String scaleStr, String offsetStr, double decay, GeoPoint docValue)`
|
|
|
|
* `double decayGeoGauss(String originStr, String scaleStr, String offsetStr, double decay, GeoPoint docValue)`
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "decayGeoExp(params.origin, params.scale, params.offset, params.decay, doc['location'].value)",
|
|
"params": {
|
|
"origin": "40, -70.12",
|
|
"scale": "200km",
|
|
"offset": "0km",
|
|
"decay" : 0.2
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
|
|
===== Decay functions for date fields
|
|
|
|
* `double decayDateLinear(String originStr, String scaleStr, String offsetStr, double decay, JodaCompatibleZonedDateTime docValueDate)`
|
|
|
|
* `double decayDateExp(String originStr, String scaleStr, String offsetStr, double decay, JodaCompatibleZonedDateTime docValueDate)`
|
|
|
|
* `double decayDateGauss(String originStr, String scaleStr, String offsetStr, double decay, JodaCompatibleZonedDateTime docValueDate)`
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "decayDateGauss(params.origin, params.scale, params.offset, params.decay, doc['date'].value)",
|
|
"params": {
|
|
"origin": "2008-01-01T01:00:00Z",
|
|
"scale": "1h",
|
|
"offset" : "0",
|
|
"decay" : 0.5
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
NOTE: Decay functions on dates are limited to dates in the default format
|
|
and default time zone. Also calculations with `now` are not supported.
|
|
|
|
|
|
==== Faster alternatives
|
|
Script Score Query calculates the score for every hit (matching document).
|
|
There are faster alternative query types that can efficiently skip
|
|
non-competitive hits:
|
|
|
|
* If you want to boost documents on some static fields, use
|
|
<<query-dsl-feature-query, Feature Query>>.
|
|
|
|
|
|
==== Transition from Function Score Query
|
|
We are deprecating <<query-dsl-function-score-query, Function Score>>, and
|
|
Script Score Query will be a substitute for it.
|
|
|
|
Here we describe how Function Score Query's functions can be
|
|
equivalently implemented in Script Score Query:
|
|
|
|
===== `script_score`
|
|
What you used in `script_score` of the Function Score query, you
|
|
can copy into the Script Score query. No changes here.
|
|
|
|
===== `weight`
|
|
`weight` function can be implemented in the Script Score query through
|
|
the following script:
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "params.weight * _score",
|
|
"params": {
|
|
"weight": 2
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
===== `random_score`
|
|
|
|
Use `randomReproducible` and `randomNotReproducible` functions
|
|
as described in <<random-functions, random functions>>.
|
|
|
|
|
|
===== `field_value_factor`
|
|
`field_value_factor` function can be easily implemented through script:
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "Math.log10(doc['field'].value * params.factor)",
|
|
params" : {
|
|
"factor" : 5
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
|
|
For checking if a document has a missing value, you can use
|
|
`doc['field'].size() == 0`. For example, this script will use
|
|
a value `1` if a document doesn't have a field `field`:
|
|
|
|
[source,js]
|
|
--------------------------------------------------
|
|
"script" : {
|
|
"source" : "Math.log10((doc['field'].size() == 0 ? 1 : doc['field'].value()) * params.factor)",
|
|
params" : {
|
|
"factor" : 5
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// NOTCONSOLE
|
|
|
|
This table lists how `field_value_factor` modifiers can be implemented
|
|
through a script:
|
|
|
|
[cols="<,<",options="header",]
|
|
|=======================================================================
|
|
| Modifier | Implementation in Script Score
|
|
|
|
| `none` | -
|
|
| `log` | `Math.log10(doc['f'].value)`
|
|
| `log1p` | `Math.log10(doc['f'].value + 1)`
|
|
| `log2p` | `Math.log10(doc['f'].value + 2)`
|
|
| `ln` | `Math.log(doc['f'].value)`
|
|
| `ln1p` | `Math.log(doc['f'].value + 1)`
|
|
| `ln2p` | `Math.log(doc['f'].value + 2)`
|
|
| `square` | `Math.pow(doc['f'].value, 2)`
|
|
| `sqrt` | `Math.sqrt(doc['f'].value)`
|
|
| `reciprocal` | `1.0 / doc['f'].value`
|
|
|=======================================================================
|
|
|
|
|
|
===== `decay functions`
|
|
Script Score query has equivalent <<decay-functions, decay functions>>
|
|
that can be used in script.
|
|
|
|
|
|
|