Global Search

It's possible to include external objects in Global Search results:

However, it won't automatically search them. Users must click on the external object name of the left hand sidebar after running the search.

How it works

When Salesforce Connect searches an external object, Omnata will run a query which includes a series of OR filters for each included String-type field, effectively searching for the presence of the search term within the text of that field.

Therefore, in order for the searches to work, you must include at least one text field in the Search Results layout for that external object:

Note that you can include other types of fields in the search results, but their contents won't be subject to the search term filtering.