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6940b2b8c7
* Scripting: Remove groovy scripting language Groovy was deprecated in 5.0. This change removes it, along with the legacy default language infrastructure in scripting.
261 lines
7.9 KiB
Plaintext
261 lines
7.9 KiB
Plaintext
[[modules-scripting-using]]
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=== How to use scripts
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Wherever scripting is supported in the Elasticsearch API, the syntax follows
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the same pattern:
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[source,js]
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-------------------------------------
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"script": {
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"lang": "...", <1>
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"inline" | "stored" | "file": "...", <2>
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"params": { ... } <3>
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}
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-------------------------------------
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<1> The language the script is written in, which defaults to `painless`.
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<2> The script itself which may be specified as `inline`, `stored`, or `file`.
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<3> Any named parameters that should be passed into the script.
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For example, the following script is used in a search request to return a
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<<search-request-script-fields, scripted field>>:
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[source,js]
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-------------------------------------
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PUT my_index/my_type/1
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{
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"my_field": 5
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}
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GET my_index/_search
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{
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"script_fields": {
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"my_doubled_field": {
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"script": {
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"lang": "expression",
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"inline": "doc['my_field'] * multiplier",
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"params": {
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"multiplier": 2
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}
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}
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}
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}
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}
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-------------------------------------
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// CONSOLE
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[float]
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=== Script Parameters
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`lang`::
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Specifies the language the script is written in. Defaults to `painless` but
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may be set to any of languages listed in <<modules-scripting>>. The
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default language may be changed in the `elasticsearch.yml` config file by
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setting `script.default_lang` to the appropriate language.
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`inline`, `id`, `file`::
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Specifies the source of the script. An `inline` script is specified
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`inline` as in the example above, a stored script with the specified `id`
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is retrieved from the cluster state (see <<modules-scripting-stored-scripts,Stored Scripts>>),
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and a `file` script is retrieved from a file in the `config/scripts`
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directory (see <<modules-scripting-file-scripts, File Scripts>>).
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+
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While languages like `expression` and `painless` can be used out of the box as
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inline or stored scripts, other languages can only be
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specified as `file` unless you first adjust the default
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<<modules-scripting-security,scripting security settings>>.
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`params`::
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Specifies any named parameters that are passed into the script as
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variables.
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[IMPORTANT]
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[[prefer-params]]
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.Prefer parameters
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========================================
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The first time Elasticsearch sees a new script, it compiles it and stores the
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compiled version in a cache. Compilation can be a heavy process.
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If you need to pass variables into the script, you should pass them in as
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named `params` instead of hard-coding values into the script itself. For
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example, if you want to be able to multiply a field value by different
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multipliers, don't hard-code the multiplier into the script:
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[source,js]
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----------------------
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"inline": "doc['my_field'] * 2"
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----------------------
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Instead, pass it in as a named parameter:
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[source,js]
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----------------------
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"inline": "doc['my_field'] * multiplier",
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"params": {
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"multiplier": 2
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}
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----------------------
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The first version has to be recompiled every time the multiplier changes. The
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second version is only compiled once.
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If you compile too many unique scripts within a small amount of time,
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Elasticsearch will reject the new dynamic scripts with a
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`circuit_breaking_exception` error. By default, up to 15 inline scripts per
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minute will be compiled. You can change this setting dynamically by setting
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`script.max_compilations_per_minute`.
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========================================
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[float]
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[[modules-scripting-file-scripts]]
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=== File-based Scripts
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To increase security, non-sandboxed languages can only be specified in script
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files stored on every node in the cluster. File scripts must be saved in the
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`scripts` directory whose default location depends on whether you use the
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<<zip-targz-layout,`zip`/`tar.gz`>> (`$ES_HOME/config/scripts/`),
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<<rpm-layout,RPM>>, or <<deb-layout,Debian>> package. The default may be
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changed with the `path.scripts` setting.
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The languages which are assumed to be safe by default are: `painless`,
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`expression`, and `mustache` (used for search and query templates).
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Any files placed in the `scripts` directory will be compiled automatically
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when the node starts up and then <<reload-scripts,every 60 seconds thereafter>>.
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The file should be named as follows: `{script-name}.{lang}`. For instance,
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the following example creates a Groovy script called `calculate-score`:
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[source,sh]
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--------------------------------------------------
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cat "Math.log(_score * 2) + my_modifier" > config/scripts/calculate-score.painless
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--------------------------------------------------
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This script can be used as follows:
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[source,js]
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--------------------------------------------------
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GET my_index/_search
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{
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"query": {
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"script": {
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"script": {
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"lang": "painless", <1>
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"file": "calculate-score", <2>
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"params": {
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"my_modifier": 2
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}
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}
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}
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}
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}
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--------------------------------------------------
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<1> The language of the script, which should correspond with the script file suffix.
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<2> The name of the script, which should be the name of the file.
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The `script` directory may contain sub-directories, in which case the
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hierarchy of directories is flattened and concatenated with underscores. A
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script in `group1/group2/my_script.painless` should use `group1_group2_myscript`
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as the `file` name.
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[[reload-scripts]]
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[float]
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==== Automatic script reloading
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The `scripts` directory will be rescanned every `60s` (configurable with the
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`resource.reload.interval` setting) and new, changed, or removed scripts will
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be compiled, updated, or deleted from the script cache.
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Script reloading can be completely disabled by setting
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`script.auto_reload_enabled` to `false`.
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[float]
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[[modules-scripting-stored-scripts]]
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=== Stored Scripts
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Scripts may be stored in and retrieved from the cluster state using the
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`_scripts` end-point:
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[source,js]
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-----------------------------------
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/_scripts/{lang}/{id} <1> <2>
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-----------------------------------
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<1> The `lang` represents the script language.
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<2> The `id` is a unique identifier or script name.
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This example stores a Painless script called `calculate-score` in the cluster
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state:
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[source,js]
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-----------------------------------
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POST _scripts/painless/calculate-score
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{
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"script": "Math.log(_score * 2) + params.my_modifier"
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}
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-----------------------------------
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// CONSOLE
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This same script can be retrieved with:
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[source,js]
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-----------------------------------
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GET _scripts/painless/calculate-score
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-----------------------------------
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// CONSOLE
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// TEST[continued]
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Stored scripts can be used by specifying the `lang` and `stored` parameters as follows:
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[source,js]
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--------------------------------------------------
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GET _search
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{
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"query": {
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"script": {
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"script": {
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"lang": "painless",
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"stored": "calculate-score",
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"params": {
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"my_modifier": 2
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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// TEST[continued]
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And deleted with:
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[source,js]
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-----------------------------------
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DELETE _scripts/painless/calculate-score
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-----------------------------------
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// CONSOLE
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// TEST[continued]
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[float]
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[[modules-scripting-using-caching]]
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=== Script Caching
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All scripts are cached by default so that they only need to be recompiled
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when updates occur. File scripts keep a static cache and will always reside
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in memory. Both inline and stored scripts are stored in a cache that can evict
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residing scripts. By default, scripts do not have a time-based expiration, but
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you can change this behavior by using the `script.cache.expire` setting.
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You can configure the size of this cache by using the `script.cache.max_size` setting.
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By default, the cache size is `100`.
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NOTE: The size of stored scripts is limited to 65,535 bytes. This can be
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changed by setting `script.max_size_in_bytes` setting to increase that soft
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limit, but if scripts are really large then alternatives like
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<<modules-scripting-native,native>> scripts should be considered instead.
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