433 lines
10 KiB
Plaintext
433 lines
10 KiB
Plaintext
[[modules-scripting-using]]
|
|
== How to use scripts
|
|
|
|
Wherever scripting is supported in the Elasticsearch API, the syntax follows
|
|
the same pattern:
|
|
|
|
[source,js]
|
|
-------------------------------------
|
|
"script": {
|
|
"lang": "...", <1>
|
|
"source" | "id": "...", <2>
|
|
"params": { ... } <3>
|
|
}
|
|
-------------------------------------
|
|
// NOTCONSOLE
|
|
<1> The language the script is written in, which defaults to `painless`.
|
|
<2> The script itself which may be specified as `source` for an inline script or `id` for a stored script.
|
|
<3> Any named parameters that should be passed into the script.
|
|
|
|
For example, the following script is used in a search request to return a
|
|
<<request-body-search-script-fields, scripted field>>:
|
|
|
|
[source,console]
|
|
-------------------------------------
|
|
PUT my-index-000001/_doc/1
|
|
{
|
|
"my_field": 5
|
|
}
|
|
|
|
GET my-index-000001/_search
|
|
{
|
|
"script_fields": {
|
|
"my_doubled_field": {
|
|
"script": {
|
|
"lang": "expression",
|
|
"source": "doc['my_field'] * multiplier",
|
|
"params": {
|
|
"multiplier": 2
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
-------------------------------------
|
|
|
|
[discrete]
|
|
=== Script parameters
|
|
|
|
`lang`::
|
|
|
|
Specifies the language the script is written in. Defaults to `painless`.
|
|
|
|
|
|
`source`, `id`::
|
|
|
|
Specifies the source of the script. An `inline` script is specified
|
|
`source` as in the example above. A `stored` script is specified `id`
|
|
and is retrieved from the cluster state (see <<modules-scripting-stored-scripts,Stored Scripts>>).
|
|
|
|
|
|
`params`::
|
|
|
|
Specifies any named parameters that are passed into the script as
|
|
variables.
|
|
|
|
[IMPORTANT]
|
|
[[prefer-params]]
|
|
.Prefer parameters
|
|
========================================
|
|
|
|
The first time Elasticsearch sees a new script, it compiles it and stores the
|
|
compiled version in a cache. Compilation can be a heavy process.
|
|
|
|
If you need to pass variables into the script, you should pass them in as
|
|
named `params` instead of hard-coding values into the script itself. For
|
|
example, if you want to be able to multiply a field value by different
|
|
multipliers, don't hard-code the multiplier into the script:
|
|
|
|
[source,js]
|
|
----------------------
|
|
"source": "doc['my_field'] * 2"
|
|
----------------------
|
|
// NOTCONSOLE
|
|
|
|
Instead, pass it in as a named parameter:
|
|
|
|
[source,js]
|
|
----------------------
|
|
"source": "doc['my_field'] * multiplier",
|
|
"params": {
|
|
"multiplier": 2
|
|
}
|
|
----------------------
|
|
// NOTCONSOLE
|
|
|
|
The first version has to be recompiled every time the multiplier changes. The
|
|
second version is only compiled once.
|
|
|
|
If you compile too many unique scripts within a small amount of time,
|
|
Elasticsearch will reject the new dynamic scripts with a
|
|
`circuit_breaking_exception` error. By default, up to 75 scripts per
|
|
5 minutes will be compiled for most contexts and 375 scripts per 5 minutes
|
|
for `ingest` contexts. You can change these settings dynamically by setting
|
|
`script.context.$CONTEXT.max_compilations_rate` e.g.,
|
|
`script.context.field.max_compilations_rate=100/10m`.
|
|
|
|
========================================
|
|
|
|
[discrete]
|
|
[[modules-scripting-short-script-form]]
|
|
=== Short script form
|
|
A short script form can be used for brevity. In the short form, `script` is represented
|
|
by a string instead of an object. This string contains the source of the script.
|
|
|
|
Short form:
|
|
|
|
[source,js]
|
|
----------------------
|
|
"script": "ctx._source.my-int++"
|
|
----------------------
|
|
// NOTCONSOLE
|
|
|
|
The same script in the normal form:
|
|
|
|
[source,js]
|
|
----------------------
|
|
"script": {
|
|
"source": "ctx._source.my-int++"
|
|
}
|
|
----------------------
|
|
// NOTCONSOLE
|
|
|
|
[discrete]
|
|
[[modules-scripting-stored-scripts]]
|
|
=== Stored scripts
|
|
|
|
Scripts may be stored in and retrieved from the cluster state using the
|
|
`_scripts` end-point.
|
|
|
|
If the {es} {security-features} are enabled, you must have the following
|
|
privileges to create, retrieve, and delete stored scripts:
|
|
|
|
* cluster: `all` or `manage`
|
|
|
|
For more information, see <<security-privileges>>.
|
|
|
|
|
|
[discrete]
|
|
==== Request examples
|
|
|
|
The following are examples of using a stored script that lives at
|
|
`/_scripts/{id}`.
|
|
|
|
First, create the script called `calculate-score` in the cluster state:
|
|
|
|
[source,console]
|
|
-----------------------------------
|
|
POST _scripts/calculate-score
|
|
{
|
|
"script": {
|
|
"lang": "painless",
|
|
"source": "Math.log(_score * 2) + params.my_modifier"
|
|
}
|
|
}
|
|
-----------------------------------
|
|
// TEST[setup:my_index]
|
|
|
|
You may also specify a context as part of the url path to compile a
|
|
stored script against that specific context in the form of
|
|
`/_scripts/{id}/{context}`:
|
|
|
|
[source,console]
|
|
-----------------------------------
|
|
POST _scripts/calculate-score/score
|
|
{
|
|
"script": {
|
|
"lang": "painless",
|
|
"source": "Math.log(_score * 2) + params.my_modifier"
|
|
}
|
|
}
|
|
-----------------------------------
|
|
// TEST[setup:my_index]
|
|
|
|
This same script can be retrieved with:
|
|
|
|
[source,console]
|
|
-----------------------------------
|
|
GET _scripts/calculate-score
|
|
-----------------------------------
|
|
// TEST[continued]
|
|
|
|
Stored scripts can be used by specifying the `id` parameters as follows:
|
|
|
|
[source,console]
|
|
--------------------------------------------------
|
|
GET my-index-000001/_search
|
|
{
|
|
"query": {
|
|
"script_score": {
|
|
"query": {
|
|
"match": {
|
|
"message": "some message"
|
|
}
|
|
},
|
|
"script": {
|
|
"id": "calculate-score",
|
|
"params": {
|
|
"my_modifier": 2
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// TEST[continued]
|
|
|
|
And deleted with:
|
|
|
|
[source,console]
|
|
-----------------------------------
|
|
DELETE _scripts/calculate-score
|
|
-----------------------------------
|
|
// TEST[continued]
|
|
|
|
[discrete]
|
|
[[modules-scripting-search-templates]]
|
|
=== Search templates
|
|
You can also use the `_scripts` API to store **search templates**. Search
|
|
templates save specific <<search-search,search requests>> with placeholder
|
|
values, called template parameters.
|
|
|
|
You can use stored search templates to run searches without writing out the
|
|
entire query. Just provide the stored template's ID and the template parameters.
|
|
This is useful when you want to run a commonly used query quickly and without
|
|
mistakes.
|
|
|
|
Search templates use the https://mustache.github.io/mustache.5.html[mustache
|
|
templating language]. See <<search-template>> for more information and examples.
|
|
|
|
[discrete]
|
|
[[modules-scripting-using-caching]]
|
|
=== Script caching
|
|
|
|
All scripts are cached by default so that they only need to be recompiled
|
|
when updates occur. By default, scripts do not have a time-based expiration, but
|
|
you can configure the size of this cache using the
|
|
`script.context.$CONTEXT.cache_expire` setting.
|
|
By default, the cache size is `100` for all contexts except the `ingest` and the
|
|
`processor_conditional` context, where it is `200`.
|
|
|
|
|====
|
|
| Context | Default Cache Size
|
|
| `ingest` | 200
|
|
| `processor_conditional` | 200
|
|
| default | 100
|
|
|====
|
|
|
|
NOTE: The size of scripts is limited to 65,535 bytes. This can be
|
|
changed by setting `script.max_size_in_bytes` setting to increase that soft
|
|
limit, but if scripts are really large then a
|
|
<<modules-scripting-engine,native script engine>> should be considered.
|
|
|
|
[[scripts-and-search-speed]]
|
|
=== Scripts and search speed
|
|
|
|
Scripts can't make use of {es}'s index structures or related optimizations. This
|
|
can sometimes result in slower search speeds.
|
|
|
|
If you often use scripts to transform indexed data, you can speed up search by
|
|
making these changes during ingest instead. However, that often means slower
|
|
index speeds.
|
|
|
|
.*Example*
|
|
[%collapsible]
|
|
=====
|
|
An index, `my_test_scores`, contains two `long` fields:
|
|
|
|
* `math_score`
|
|
* `verbal_score`
|
|
|
|
When running searches, users often use a script to sort results by the sum of
|
|
these two field's values.
|
|
|
|
[source,console]
|
|
----
|
|
GET /my_test_scores/_search
|
|
{
|
|
"query": {
|
|
"term": {
|
|
"grad_year": "2099"
|
|
}
|
|
},
|
|
"sort": [
|
|
{
|
|
"_script": {
|
|
"type": "number",
|
|
"script": {
|
|
"source": "doc['math_score'].value + doc['verbal_score'].value"
|
|
},
|
|
"order": "desc"
|
|
}
|
|
}
|
|
]
|
|
}
|
|
----
|
|
// TEST[s/^/PUT my_test_scores\n/]
|
|
|
|
To speed up search, you can perform this calculation during ingest and index the
|
|
sum to a field instead.
|
|
|
|
First, <<indices-put-mapping,add a new field>>, `total_score`, to the index. The
|
|
`total_score` field will contain sum of the `math_score` and `verbal_score`
|
|
field values.
|
|
|
|
[source,console]
|
|
----
|
|
PUT /my_test_scores/_mapping
|
|
{
|
|
"properties": {
|
|
"total_score": {
|
|
"type": "long"
|
|
}
|
|
}
|
|
}
|
|
----
|
|
// TEST[continued]
|
|
|
|
Next, use an <<ingest,ingest pipeline>> containing the
|
|
<<script-processor,`script`>> processor to calculate the sum of `math_score` and
|
|
`verbal_score` and index it in the `total_score` field.
|
|
|
|
[source,console]
|
|
----
|
|
PUT _ingest/pipeline/my_test_scores_pipeline
|
|
{
|
|
"description": "Calculates the total test score",
|
|
"processors": [
|
|
{
|
|
"script": {
|
|
"source": "ctx.total_score = (ctx.math_score + ctx.verbal_score)"
|
|
}
|
|
}
|
|
]
|
|
}
|
|
----
|
|
// TEST[continued]
|
|
|
|
To update existing data, use this pipeline to <<docs-reindex,reindex>> any
|
|
documents from `my_test_scores` to a new index, `my_test_scores_2`.
|
|
|
|
[source,console]
|
|
----
|
|
POST /_reindex
|
|
{
|
|
"source": {
|
|
"index": "my_test_scores"
|
|
},
|
|
"dest": {
|
|
"index": "my_test_scores_2",
|
|
"pipeline": "my_test_scores_pipeline"
|
|
}
|
|
}
|
|
----
|
|
// TEST[continued]
|
|
|
|
Continue using the pipeline to index any new documents to `my_test_scores_2`.
|
|
|
|
[source,console]
|
|
----
|
|
POST /my_test_scores_2/_doc/?pipeline=my_test_scores_pipeline
|
|
{
|
|
"student": "kimchy",
|
|
"grad_year": "2099",
|
|
"math_score": 800,
|
|
"verbal_score": 800
|
|
}
|
|
----
|
|
// TEST[continued]
|
|
|
|
These changes may slow indexing but allow for faster searches. Users can now
|
|
sort searches made on `my_test_scores_2` using the `total_score` field instead
|
|
of using a script.
|
|
|
|
[source,console]
|
|
----
|
|
GET /my_test_scores_2/_search
|
|
{
|
|
"query": {
|
|
"term": {
|
|
"grad_year": "2099"
|
|
}
|
|
},
|
|
"sort": [
|
|
{
|
|
"total_score": {
|
|
"order": "desc"
|
|
}
|
|
}
|
|
]
|
|
}
|
|
----
|
|
// TEST[continued]
|
|
|
|
////
|
|
[source,console]
|
|
----
|
|
DELETE /_ingest/pipeline/my_test_scores_pipeline
|
|
----
|
|
// TEST[continued]
|
|
|
|
[source,console-result]
|
|
----
|
|
{
|
|
"acknowledged": true
|
|
}
|
|
----
|
|
////
|
|
=====
|
|
|
|
We recommend testing and benchmarking any indexing changes before deploying them
|
|
in production.
|
|
|
|
[discrete]
|
|
[[modules-scripting-errors]]
|
|
=== Script errors
|
|
Elasticsearch returns error details when there is a compliation or runtime
|
|
exception. The contents of this response are useful for tracking down the
|
|
problem.
|
|
|
|
experimental[]
|
|
|
|
The contents of `position` are experimental and subject to change.
|