Field Capabilities API | ElasticSearch 7.7 权威指南中文版

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Field Capabilities APIedit

Allows you to retrieve the capabilities of fields among multiple indices.

GET /_field_caps?fields=rating

Requestedit

GET /_field_caps

POST /_field_caps

GET /<index>/_field_caps

POST /<index>/_field_caps

Descriptionedit

The field capabilities API returns the information about the capabilities of fields among multiple indices.

Path parametersedit

<index>: (Optional, string) Comma-separated list or wildcard expression of index names used to limit the request.

Query parametersedit

allow_no_indices

(Optional, boolean) If true, the request does not return an error if a wildcard expression or _all value retrieves only missing or closed indices.

This parameter also applies to index aliases that point to a missing or closed index.

Defaults to true.

expand_wildcards

(Optional, string) Controls what kind of indices that wildcard expressions can expand to. Multiple values are accepted when separated by a comma, as in open,hidden. Valid values are:

all: Expand to open and closed indices, including hidden indices.
open: Expand only to open indices.
closed: Expand only to closed indices.
hidden: Expansion of wildcards will include hidden indices. Must be combined with open, closed, or both.
none: Wildcard expressions are not accepted.

Defaults to open.

fields

(Optional, string) Comma-separated list or wildcard expressions of fields to include in the statistics.

Used as the default list unless a specific field list is provided in the completion_fields or fielddata_fields parameters.

ignore_unavailable

(Optional, boolean) If true, missing or closed indices are not included in the response. Defaults to false.

include_unmapped

(Optional, boolean) If true, unmapped fields are included in the response. Defaults to false.

Response bodyedit

searchable: Whether this field is indexed for search on all indices.
aggregatable: Whether this field can be aggregated on all indices.
indices: The list of indices where this field has the same type, or null if all indices have the same type for the field.
non_searchable_indices: The list of indices where this field is not searchable, or null if all indices have the same definition for the field.
non_aggregatable_indices: The list of indices where this field is not aggregatable, or null if all indices have the same definition for the field.
meta: Merged metadata across all indices as a map of string keys to arrays of values. A value length of 1 indicates that all indices had the same value for this key, while a length of 2 or more indicates that not all indices had the same value for this key.

Examplesedit

The request can be restricted to specific indices:

GET twitter/_field_caps?fields=rating

The next example API call requests information about the rating and the title fields:

GET _field_caps?fields=rating,title

The API returns the following response:

{
    "indices": ["index1", "index2", "index3", "index4", "index5"],
    "fields": {
        "rating": { 
            "long": {
                "searchable": true,
                "aggregatable": false,
                "indices": ["index1", "index2"],
                "non_aggregatable_indices": ["index1"] 
            },
            "keyword": {
                "searchable": false,
                "aggregatable": true,
                "indices": ["index3", "index4"],
                "non_searchable_indices": ["index4"] 
            }
        },
        "title": { 
            "text": {
                "searchable": true,
                "aggregatable": false

            }
        }
    }
}

	The field `rating` is defined as a long in `index1` and `index2` and as a `keyword` in `index3` and `index4`.
	The field `rating` is not aggregatable in `index1`.
	The field `rating` is not searchable in `index4`.
	The field `title` is defined as `text` in all indices.

By default unmapped fields are ignored. You can include them in the response by adding a parameter called include_unmapped in the request:

GET _field_caps?fields=rating,title&include_unmapped

In which case the response will contain an entry for each field that is present in some indices but not all:

{
    "indices": ["index1", "index2", "index3"],
    "fields": {
        "rating": {
            "long": {
                "searchable": true,
                "aggregatable": false,
                "indices": ["index1", "index2"],
                "non_aggregatable_indices": ["index1"]
            },
            "keyword": {
                "searchable": false,
                "aggregatable": true,
                "indices": ["index3", "index4"],
                "non_searchable_indices": ["index4"]
            },
            "unmapped": { 
                "indices": ["index5"],
                "searchable": false,
                "aggregatable": false
            }
        },
        "title": {
            "text": {
                "indices": ["index1", "index2", "index3", "index4"],
                "searchable": true,
                "aggregatable": false
            },
            "unmapped": { 
                "indices": ["index5"]
                "searchable": false,
                "aggregatable": false
            }
        }
    }
}

	The `rating` field is unmapped` in `index5`.
	The `title` field is unmapped` in `index5`.

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