_field_names field
edit_field_names
field
editThe _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
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 exists
query will still
be available but will not use the _field_names
field.
Disabling _field_names
editDisabling _field_names
is often 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
be adding the following to the mappings:
PUT tweets { "mappings": { "_doc": { "_field_names": { "enabled": false } } } }