Setting index.warmer.enabled is undocumented

[DaveCTurner]

The documentation for the index.warmer.enabled setting was lost in f123a53. It was almost entirely a link to the documentation about index warmers that no longer exists:

elasticsearch/docs/reference/indices/update-settings.asciidoc

Line 155 in 1df2d30

See <<indices-warmers>>. Defaults to `true`.

[elasticmachine]

Pinging @elastic/es-search-aggs

[jrodewig]

Hi @DaveCTurner

It looks like index warmers were deprecated in 2.3:
https://www.elastic.co/guide/en/elasticsearch/reference/2.4/indices-warmers.html

There also appear to be no links to indices-warmers in the current documentation.

Are you comfortable with me closing this ticket?

[DaveCTurner]

Hi @jrodewig, the index.warmer.enabled setting still exists in master:

elasticsearch/server/src/main/java/org/elasticsearch/index/IndexSettings.java

Lines 72 to 73 in 35fa582

	public static final Setting<Boolean> INDEX_WARMER_ENABLED_SETTING =
	Setting.boolSetting("index.warmer.enabled", true, Property.Dynamic, Property.IndexScope);

Although it does much less than what it used to in the 2.x series it still does something. I think we should either document it or remove it.

[jimczi]

We discussed this issue internally and decided that we should remove this setting. Today it is used for two things:

• To load the global ordinals if eager_global_ordinals is set on the field.
• To load the bitset filters for all nested fields present in the mapping.
  The former can be controlled on a per field basis while the latter can be controlled with another setting called index.load_fixed_bitset_filters_eagerly so there's no need to keep index.warmer.enabled at all.