opensearch-docs-cn/_api-reference/index-apis/clear-index-cache.md

layout	title	parent	nav_order
default	Clear cache	Index APIs	10

Clear cache

The clear cache API operation clears the caches of one or more indexes. For data streams, the API clears the caches of the stream’s backing indexes.

If you use the Security plugin, you must have the manage index privileges. {: .note}

Path parameters

Parameter	Data type	Description
target	String	Comma-delimited list of data streams, indexes, and index aliases to which cache clearing is applied. Wildcard expressions (*) are supported. To target all data streams and indexes in a cluster, omit this parameter or use _all or *. Optional.

Query parameters

All query parameters are optional.

Parameter	Data type	Description
allow_no_indices	Boolean	Whether to ignore wildcards, index aliases, or _all target (target path parameter) values that don’t match any indexes. If false, the request returns an error if any wildcard expression, index alias, or _all target value doesn't match any indexes. This behavior also applies if the request targets include other open indexes. For example, a request where the target is fig*,app* returns an error if an index starts with fig but no index starts with app. Defaults to true.
expand_wildcards	String	Determines the index types that wildcard expressions can expand to. Accepts multiple values separated by a comma, such as open,hidden. Valid values are: all -- Expand to open, closed, and hidden indexes. open -- Expand only to open indexes. closed -- Expand only to closed indexes hidden -- Expand to include hidden indexes. Must be combined with open, closed, or both. none -- Expansions are not accepted. Defaults to open.
fielddata	Boolean	If true, clears the fields cache. Use the fields parameter to clear specific fields' caches. Defaults to true.
fields	String	Used in conjunction with the fielddata parameter. Comma-delimited list of field names that are cleared out of the cache. Does not support objects or field aliases. Defaults to all fields.
file	Boolean	If true, clears the unused entries from the file cache on nodes with the Search role. Defaults to false.
index	String	Comma-delimited list of index names that are cleared out of the cache.
ignore_unavailable	Boolean	If true, OpenSearch ignores missing or closed indexes. Defaults to false.
query	Boolean	If true, clears the query cache. Defaults to true.
request	Boolean	If true, clears the request cache. Defaults to true.

Example requests

The following example requests show multiple clear cache API uses.

Clear a specific cache

The following request clears the fields cache only:

POST /my-index/_cache/clear?fielddata=true

{% include copy-curl.html %}

---

The following request clears the query cache only:

POST /my-index/_cache/clear?query=true

{% include copy-curl.html %}

---

The following request clears the request cache only:

POST /my-index/_cache/clear?request=true

{% include copy-curl.html %}

Clear the cache for specific fields

The following request clears the fields caches of fielda and fieldb:

POST /my-index/_cache/clear?fields=fielda,fieldb

{% include copy-curl.html %}

Clear caches for specific data streams or indexes

The following request clears the cache for two specific indexes:

POST /my-index,my-index2/_cache/clear

{% include copy-curl.html %}

Clear caches for all data streams and indexes

The following request clears the cache for all data streams and indexes:

POST /_cache/clear

{% include copy-curl.html %}

Clear unused entries from the cache on search-capable nodes

POST /*/_cache/clear?file=true 

{% include copy-curl.html %}

Example response

The POST /books,hockey/_cache/clear request returns the following fields:

{
  "_shards" : {
    "total" : 4,
    "successful" : 2,
    "failed" : 0
  }
}

Response fields

The POST /books,hockey/_cache/clear request returns the following response fields:

Field	Data type	Description
_shards	Object	Shard information.
total	Integer	Total number of shards.
successful	Integer	Number of index shards with caches successfully cleared.
failed	Integer	Number of index shards with caches that failed to clear.