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Add randomScore function in script_score query (#40186)
To make script_score query to have the same features as function_score query, we need to add randomScore function. This function produces different random scores on different index shards. It is also able to produce random scores based on the internal Lucene Document Ids.
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‎docs/reference/query-dsl/script-score-query.asciidoc

+22-38
Original file line numberDiff line numberDiff line change
@@ -182,60 +182,44 @@ different from the query's vector, 0 is used for missing dimensions
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in the calculations of vector functions.
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[[random-functions]]
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===== Random functions
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There are two predefined ways to produce random values:
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`randomNotReproducible` and `randomReproducible`.
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[[random-score-function]]
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===== Random score function
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`random_score` function generates scores that are uniformly distributed
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from 0 up to but not including 1.
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`randomNotReproducible()` uses `java.util.Random` class
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to generate a random value of the type `long`.
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The generated values are not reproducible between requests' invocations.
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`randomScore` function has the following syntax:
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`randomScore(<seed>, <fieldName>)`.
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It has a required parameter - `seed` as an integer value,
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and an optional parameter - `fieldName` as a string value.
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[source,js]
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--------------------------------------------------
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"script" : {
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"source" : "randomNotReproducible()"
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"source" : "randomScore(100, '_seq_no')"
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}
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--------------------------------------------------
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// NOTCONSOLE
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`randomReproducible(String seedValue, int seed)` produces
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reproducible random values of type `long`. This function requires
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more computational time and memory than the non-reproducible version.
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A good candidate for the `seedValue` is document field values that
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are unique across documents and already pre-calculated and preloaded
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in the memory. For example, values of the document's `_seq_no` field
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is a good candidate, as documents on the same shard have unique values
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for the `_seq_no` field.
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If the `fieldName` parameter is omitted, the internal Lucene
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document ids will be used as a source of randomness. This is very efficient,
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but unfortunately not reproducible since documents might be renumbered
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by merges.
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[source,js]
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--------------------------------------------------
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"script" : {
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"source" : "randomReproducible(Long.toString(doc['_seq_no'].value), 100)"
211+
"source" : "randomScore(100)"
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}
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--------------------------------------------------
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// NOTCONSOLE
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A drawback of using `_seq_no` is that generated values change if
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documents are updated. Another drawback is not absolute uniqueness, as
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documents from different shards with the same sequence numbers
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generate the same random values.
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If you need random values to be distinct across different shards,
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you can use a field with unique values across shards,
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such as `_id`, but watch out for the memory usage as all
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these unique values need to be loaded into memory.
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[source,js]
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--------------------------------------------------
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"script" : {
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"source" : "randomReproducible(doc['_id'].value, 100)"
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}
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--------------------------------------------------
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// NOTCONSOLE
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Note that documents that are within the same shard and have the
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same value for field will get the same score, so it is usually desirable
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to use a field that has unique values for all documents across a shard.
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A good default choice might be to use the `_seq_no`
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field, whose only drawback is that scores will change if the document is
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updated since update operations also update the value of the `_seq_no` field.
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[[decay-functions]]
@@ -349,8 +333,8 @@ the following script:
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===== `random_score`
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Use `randomReproducible` and `randomNotReproducible` functions
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as described in <<random-functions, random functions>>.
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Use `randomScore` function
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as described in <<random-score-function, random score function>>.
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===== `field_value_factor`

‎modules/lang-painless/src/main/resources/org/elasticsearch/painless/spi/org.elasticsearch.score.txt

+5-2
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@@ -19,11 +19,14 @@
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# This file contains a whitelist for functions to be used in Score context
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class org.elasticsearch.script.ScoreScript no_import {
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}
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static_import {
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double saturation(double, double) from_class org.elasticsearch.script.ScoreScriptUtils
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double sigmoid(double, double, double) from_class org.elasticsearch.script.ScoreScriptUtils
25-
double randomReproducible(String, int) from_class org.elasticsearch.script.ScoreScriptUtils
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double randomNotReproducible() bound_to org.elasticsearch.script.ScoreScriptUtils$RandomNotReproducible
28+
double randomScore(org.elasticsearch.script.ScoreScript, int, String) bound_to org.elasticsearch.script.ScoreScriptUtils$RandomScoreField
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double randomScore(org.elasticsearch.script.ScoreScript, int) bound_to org.elasticsearch.script.ScoreScriptUtils$RandomScoreDoc
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double decayGeoLinear(String, String, String, double, GeoPoint) bound_to org.elasticsearch.script.ScoreScriptUtils$DecayGeoLinear
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double decayGeoExp(String, String, String, double, GeoPoint) bound_to org.elasticsearch.script.ScoreScriptUtils$DecayGeoExp
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double decayGeoGauss(String, String, String, double, GeoPoint) bound_to org.elasticsearch.script.ScoreScriptUtils$DecayGeoGauss

‎modules/lang-painless/src/test/resources/rest-api-spec/test/painless/80_script_score.yml

-55
Original file line numberDiff line numberDiff line change
@@ -72,61 +72,6 @@ setup:
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- match: { hits.hits.1._id: d2 }
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- match: { hits.hits.2._id: d1 }
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---
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"Random functions":
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- do:
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indices.create:
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index: test
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body:
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settings:
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number_of_shards: 2
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mappings:
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properties:
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f1:
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type: keyword
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- do:
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index:
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index: test
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id: 1
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body: {"f1": "v1"}
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- do:
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index:
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index: test
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id: 2
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body: {"f1": "v2"}
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- do:
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index:
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index: test
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id: 3
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body: {"f1": "v3"}
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- do:
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indices.refresh: {}
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- do:
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search:
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rest_total_hits_as_int: true
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index: test
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body:
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query:
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script_score:
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query: {match_all: {} }
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script:
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source: "randomReproducible(Long.toString(doc['_seq_no'].value), 100)"
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- match: { hits.total: 3 }
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- do:
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search:
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rest_total_hits_as_int: true
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index: test
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body:
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query:
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script_score:
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query: {match_all: {} }
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script:
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source: "randomNotReproducible()"
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- match: { hits.total: 3 }
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---
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"Decay geo functions":
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- do:

‎modules/lang-painless/src/test/resources/rest-api-spec/test/painless/85_script_score_random_score.yml

+146
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,146 @@
1+
# Integration tests for ScriptScoreQuery using Painless
2+
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setup:
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- skip:
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version: " - 7.09.99"
6+
reason: "random score function of script score was added in 7.1"
7+
8+
---
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"Random score function with _seq_no field":
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- do:
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indices.create:
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index: test
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body:
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settings:
15+
number_of_shards: 2
16+
mappings:
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properties:
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f1:
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type: keyword
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- do:
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bulk:
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refresh: true
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body:
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v0"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v1"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v2"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v3"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v4"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v5"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v6"}'
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- do:
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search:
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rest_total_hits_as_int: true
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index: test
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body:
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query:
46+
script_score:
47+
query: {match_all: {} }
48+
script:
49+
source: "randomScore(100, '_seq_no')"
50+
# stash ids to check for reproducibility of ranking
51+
- set: { hits.hits.0._id: id0 }
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- set: { hits.hits.1._id: id1 }
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- set: { hits.hits.2._id: id2 }
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- set: { hits.hits.3._id: id3 }
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- set: { hits.hits.4._id: id4 }
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- set: { hits.hits.5._id: id5 }
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- set: { hits.hits.6._id: id6 }
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# check that ranking is reproducible
60+
- do:
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search:
62+
rest_total_hits_as_int: true
63+
index: test
64+
body:
65+
query:
66+
script_score:
67+
query: {match_all: {} }
68+
script:
69+
source: "randomScore(100, '_seq_no')"
70+
- match: { hits.hits.0._id: $id0 }
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- match: { hits.hits.1._id: $id1 }
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- match: { hits.hits.2._id: $id2 }
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- match: { hits.hits.3._id: $id3 }
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- match: { hits.hits.4._id: $id4 }
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- match: { hits.hits.5._id: $id5 }
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- match: { hits.hits.6._id: $id6 }
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78+
---
79+
"Random score function with internal doc Ids":
80+
- do:
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indices.create:
82+
index: test
83+
body:
84+
settings:
85+
number_of_shards: 1
86+
mappings:
87+
properties:
88+
f1:
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type: keyword
90+
91+
- do:
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bulk:
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refresh: true
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body:
95+
- '{"index": {"_index": "test"}}'
96+
- '{"f1": "v0"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v1"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v2"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v3"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v4"}'
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- '{"index": {"_index": "test"}}'
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- '{"f1": "v5"}'
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- '{"index": {"_index": "test"}}'
108+
- '{"f1": "v6"}'
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- do:
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search:
112+
rest_total_hits_as_int: true
113+
index: test
114+
body:
115+
query:
116+
script_score:
117+
query: {match_all: {} }
118+
script:
119+
source: "randomScore(100)"
120+
# stash ids to check for reproducibility of ranking
121+
- set: { hits.hits.0._id: id0 }
122+
- set: { hits.hits.1._id: id1 }
123+
- set: { hits.hits.2._id: id2 }
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- set: { hits.hits.3._id: id3 }
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- set: { hits.hits.4._id: id4 }
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- set: { hits.hits.5._id: id5 }
127+
- set: { hits.hits.6._id: id6 }
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# check that ranking is reproducible
130+
- do:
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search:
132+
rest_total_hits_as_int: true
133+
index: test
134+
body:
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query:
136+
script_score:
137+
query: {match_all: {} }
138+
script:
139+
source: "randomScore(100)"
140+
- match: { hits.hits.0._id: $id0 }
141+
- match: { hits.hits.1._id: $id1 }
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- match: { hits.hits.2._id: $id2 }
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- match: { hits.hits.3._id: $id3 }
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- match: { hits.hits.4._id: $id4 }
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- match: { hits.hits.5._id: $id5 }
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- match: { hits.hits.6._id: $id6 }

‎server/src/main/java/org/elasticsearch/common/lucene/search/function/ScriptScoreFunction.java

+15
Original file line numberDiff line numberDiff line change
@@ -50,18 +50,33 @@ public float score() {
5050

5151
private final ScoreScript.LeafFactory script;
5252

53+
private final int shardId;
54+
private final String indexName;
55+
5356

5457
public ScriptScoreFunction(Script sScript, ScoreScript.LeafFactory script) {
5558
super(CombineFunction.REPLACE);
5659
this.sScript = sScript;
5760
this.script = script;
61+
this.indexName = null;
62+
this.shardId = -1;
63+
}
64+
65+
public ScriptScoreFunction(Script sScript, ScoreScript.LeafFactory script, String indexName, int shardId) {
66+
super(CombineFunction.REPLACE);
67+
this.sScript = sScript;
68+
this.script = script;
69+
this.indexName = indexName;
70+
this.shardId = shardId;
5871
}
5972

6073
@Override
6174
public LeafScoreFunction getLeafScoreFunction(LeafReaderContext ctx) throws IOException {
6275
final ScoreScript leafScript = script.newInstance(ctx);
6376
final CannedScorer scorer = new CannedScorer();
6477
leafScript.setScorer(scorer);
78+
leafScript._setIndexName(indexName);
79+
leafScript._setShard(shardId);
6580
return new LeafScoreFunction() {
6681
@Override
6782
public double score(int docId, float subQueryScore) throws IOException {

‎server/src/main/java/org/elasticsearch/index/query/functionscore/ScriptScoreFunctionBuilder.java

+1-1
Original file line numberDiff line numberDiff line change
@@ -94,7 +94,7 @@ protected ScoreFunction doToFunction(QueryShardContext context) {
9494
try {
9595
ScoreScript.Factory factory = context.getScriptService().compile(script, ScoreScript.CONTEXT);
9696
ScoreScript.LeafFactory searchScript = factory.newFactory(script.getParams(), context.lookup());
97-
return new ScriptScoreFunction(script, searchScript);
97+
return new ScriptScoreFunction(script, searchScript, context.index().getName(), context.getShardId());
9898
} catch (Exception e) {
9999
throw new QueryShardException(context, "script_score: the script could not be loaded", e);
100100
}

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