The discover:searchFieldsFromSource advanced setting allowed users to switch back to the old behavior of using _source for search requests instead of the fields option. This setting only affects internal request logic to Elasticsearch for rendering the Discover grid and fields sidebar.
We will remove this setting and all associated code/tests in v9.0 to reduce code complexity in Discover, as it has been 3 years since the switch to the fields API.
The discover:searchFieldsFromSource advanced setting allowed users to switch back to the old behavior of using _source for search requests instead of the fields option. This setting only affects internal request logic to Elasticsearch for rendering the Discover grid and fields sidebar.
We will remove this setting and all associated code/tests in v9.0 to reduce code complexity in Discover, as it has been 3 years since the switch to the fields API.