However, I am able to achieve the required output using additional-query
in options as follows:
xquery version "1.0-ml";
import module namespace search = "http://marklogic.com/appservices/search"
at "/MarkLogic/appservices/search/search.xqy";
let $options :=
<options xmlns="http://marklogic.com/appservices/search">
<additional-query>{cts:collection-query("Biography")}
</additional-query>
<constraint name="Search_Element">
<range collation="http://marklogic.com/collation/"
type="xs:string" >
<element name="year"/>
</range>
</constraint>
<suggestion-source ref="Search_Element">
<range collation="http://marklogic.com/collation/"
type="xs:string" >
<element name="year"/>
</range>
</suggestion-source>
</options>
return
search:suggest("Search_Element:20", $options)
Still, I was wondering how could it be done without using additional-query paramater because it would be more optimized to use collection constraint for above.