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ES|QL metadata fields

Serverless Stack

ES|QL can access metadata fields.

To access these fields, use the METADATA directive with the FROM source command. For example:

 FROM index METADATA _index, _id

The following metadata fields are available in ES|QL:

Metadata field Type Description
_id keyword Unique document ID.
_ignored keyword Names every field in a document that was ignored when the document was indexed.
_index keyword Index name.
_index_mode keyword Index mode. For example: standard, lookup, or logsdb.
_score float Query relevance score (when enabled). Scores are updated when using full text search functions.
_source Special _source type Original JSON document body passed at index time (or a reconstructed version if synthetic _source is enabled).
_version long Document version number
  • Metadata fields are only available when the data source is an index
  • The _source type is not supported by functions
  • Only the FROM command supports the METADATA directive
  • Once enabled, metadata fields work like regular index fields

Once enabled, metadata fields are available to subsequent processing commands, just like other index fields:

 FROM ul_logs, apps METADATA _index, _version | WHERE id IN (13, 14) AND _version == 1 | EVAL key = CONCAT(_index, "_", TO_STR(id)) | SORT id, _index | KEEP id, _index, _version, key
id:long _index:keyword _version:long key:keyword
13 apps 1 apps_13
13 ul_logs 1 ul_logs_13
14 apps 1 apps_14
14 ul_logs 1 ul_logs_14

Similar to index fields, once an aggregation is performed, a metadata field will no longer be accessible to subsequent commands, unless used as a grouping field:

 FROM employees METADATA _index, _id | STATS max = MAX(emp_no) BY _index
max:integer _index:keyword
10100 employees 
 FROM products METADATA _score | WHERE MATCH(description, "wireless headphones") | SORT _score DESC | KEEP name, description, _score
Tip

Refer to ES|QL for search for more information on relevance scoring and how to use _score in your queries.