elasticsearch/docs/reference/esql/metadata-fields.asciidoc
Tommaso Teofili 1b1296ef54
Move scoring in ES|QL out of snapshot (#120354)
* Move scoring in ES|QL out of snapshot

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Co-authored-by: Carlos Delgado <6339205+carlosdelest@users.noreply.github.com>
2025-01-21 14:22:19 +01:00

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1.9 KiB
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[[esql-metadata-fields]]
=== {esql} metadata fields
++++
<titleabbrev>Metadata fields</titleabbrev>
++++
{esql} can access <<mapping-fields, metadata fields>>. The currently
supported ones are:
* <<mapping-index-field,`_index`>>: the index to which the document belongs.
The field is of the type <<keyword, keyword>>.
* <<mapping-id-field,`_id`>>: the source document's ID. The field is of the
type <<keyword, keyword>>.
* `_version`: the source document's version. The field is of the type
<<number,long>>.
* <<mapping-ignored-field,`_ignored`>>: the ignored source document fields. The field is of the type
<<keyword,keyword>>.
* `_score`: when enabled, the final score assigned to each row matching an ES|QL query. Scoring will be updated when using <<esql-search-functions,full text search functions>>.
To enable the access to these fields, the <<esql-from,`FROM`>> source command needs
to be provided with a dedicated directive:
[source,esql]
----
FROM index METADATA _index, _id
----
Metadata fields are only available if the source of the data is an index.
Consequently, `FROM` is the only source commands that supports the `METADATA`
directive.
Once enabled, these fields will be available to subsequent processing commands, just
like other index fields:
[source.merge.styled,esql]
----
include::{esql-specs}/metadata.csv-spec[tag=multipleIndices]
----
[%header.monospaced.styled,format=dsv,separator=|]
|===
include::{esql-specs}/metadata.csv-spec[tag=multipleIndices-result]
|===
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:
[source.merge.styled,esql]
----
include::{esql-specs}/metadata.csv-spec[tag=metaIndexInAggs]
----
[%header.monospaced.styled,format=dsv,separator=|]
|===
include::{esql-specs}/metadata.csv-spec[tag=metaIndexInAggs-result]
|===