37 lines
1.6 KiB
Plaintext
37 lines
1.6 KiB
Plaintext
[[mapping-field-names-field]]
|
|
=== `_field_names` field
|
|
|
|
The `_field_names` field used to index the names of every field in a document that
|
|
contains any value other than `null`. This field was used by the
|
|
<<query-dsl-exists-query,`exists`>> query to find documents that
|
|
either have or don't have any non-+null+ value for a particular field.
|
|
|
|
Now the `_field_names` field only indexes the names of fields that have
|
|
`doc_values` and `norms` disabled. For fields which have either `doc_values`
|
|
or `norm` enabled the <<query-dsl-exists-query,`exists`>> query will still
|
|
be available but will not use the `_field_names` field.
|
|
|
|
[[disable-field-names]]
|
|
==== Disabling `_field_names`
|
|
|
|
NOTE: Disabling `_field_names` has been deprecated and will be removed in a future major version.
|
|
|
|
Disabling `_field_names` is usually not necessary because it no longer
|
|
carries the index overhead it once did. If you have a lot of fields
|
|
which have `doc_values` and `norms` disabled and you do not need to
|
|
execute `exists` queries using those fields you might want to disable
|
|
`_field_names` by adding the following to the mappings:
|
|
|
|
[source,console]
|
|
--------------------------------------------------
|
|
PUT tweets
|
|
{
|
|
"mappings": {
|
|
"_field_names": {
|
|
"enabled": false
|
|
}
|
|
}
|
|
}
|
|
--------------------------------------------------
|
|
// TEST[warning:Index [tweets] uses the deprecated `enabled` setting for `_field_names`. Disabling _field_names is not necessary because it no longer carries a large index overhead. Support for this setting will be removed in a future major version. Please remove it from your mappings and templates.]
|