Stemming is a process that reduces inflected (or sometimes derived) words to their stem, base, or root form.
Primo uses stemming when a search returns fewer results than a defined threshold. By default, Primo sets the threshold for the returned results to 25. If the search returns fewer results than this amount, Primo stems the search terms using the Kstem stemmer.
On-premises customers can customize the default threshold by editing the min_res_for_stemming parameter in the search_schema.xml file. This file is located in the following directory, where <v> is the Primo version and <c> is the copy:
- Primo does not unstem terms with the exception of pluralization. If the result set is lower than the default threshold, Primo will pluralize terms, ranking their results lower. For example, a search for wild flower expands to wild AND (flower OR flowers^0.5).
- Changes to the stemming configuration files have no effect on the results returned from remote searches, Primo Central, or any other deep search adaptor.