honeymoose
/
OpenSearch
mirror of https://github.com/honeymoose/OpenSearch.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

[DOCS] Rewords _field_names documentation (#31029) 

* [DOCS] Rewords _field_names documentation

Corrects the language around when we write to `_field_names` and when you might want to disable it given that n recent versions it does not carry the indexing overhead it once did.

Relates to #30862

* Update wording following review
This commit is contained in:
Colin Goodheart-Smithe 2018-06-04 09:17:11 +01:00 committed by GitHub
parent 0427339ab0
commit 1efb1aae28
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 11 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

46
docs/reference/mapping/fields/field-names-field.asciidoc
View File

@ -1,47 +1,23 @@
[[mapping-field-names-field]]
=== `_field_names` field
The `_field_names` field indexes the names of every field in a document that
contains any value other than `null`. This field is used by the
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.
The value of the `_field_names` field is accessible in queries:
[source,js]
--------------------------
# Example documents
PUT my_index/_doc/1
{
"title": "This is a document"
}
PUT my_index/_doc/2?refresh=true
{
"title": "This is another document",
"body": "This document has a body"
}
GET my_index/_search
{
"query": {
"terms": {
"_field_names": [ "title" ] <1>
}
}
}
--------------------------
// CONSOLE
<1> Querying on the `_field_names` field (also see the <<query-dsl-exists-query,`exists`>> query)
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.
==== Disabling `_field_names`
Because `_field_names` introduce some index-time overhead, you might want to
disable this field if you want to optimize for indexing speed and do not need
`exists` queries.
Disabling `_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:
[source,js]
--------------------------------------------------