The goal of this project is to cleanly extend Search API using Search API Solr Search as backend to provide:

  • better support for non-English languages
  • support for multilingual search
  • cross-language information retrieval (CLIR)
  • an easy-to-use administration interface

Search API Multilingual Solr Search for Drupal 8.x is the successor of Apache Solr Multilingual for Drupal 7.x and 6.x.

Important News

Search API Multilingual Solr Search was merged into Search API Solr Search 8.x-2.x.
So further development will happen there.



The projects mentioned above provide a (more or less) easy way to use Apache Solr as a powerful search engine for Drupal. Unfortunately, the only language that works well with them, out-of-the-box, is English.

So if you run a non-English website, you need to tweak all the configuration files by hand or you lose some of the advantages that Solr provides compared to Drupal's built-in database-driven search. Doing so requires a deep knowledge of Solr and search technology in general.

The entire process gets even more complicated if you run a multilingual website.

That is why we started thinking about an additional module, to hide most of the complexity from a Drupal website's administrator.

Language-Specific Problems

  • Stop Words
    Words you want to exclude from your search index are called stop words. The list of words strongly depends on the focus of your website and, of course, on your site's language.
  • Stemming
    Every word in the search index is stored in a reduced form called a word stem. This strategy enables the user to find content, independent of the key word's inflection, e.g. singular or plural. Unfortunately, the stemming algorithm is different from language to language.
  • Protected Words
    In some cases, you'll want to exclude certain words from the stemming described above. These protected words are language-specific, like stop words.
  • Compound Word Splitting
    Languages like German frequently combine words (e.g. "Dampfschifffahrt"). In order to deal with that problem you need to split such words into parts depending on language-specific word catalogs.
  • Spell Checking
    No doubt that spell checking should be language-specific.

Search API Multilingual Solr Search

Search API Multilingual Solr Search provides an out-of-the-box solution to language-specific problems (described above) or supports the site administrator by providing a user interface that hides some of the complexity.

Additionally, Search API Multilingual Solr Search provides a way to offer language-specific searches for different languages at once on multilingual websites. Therefore, Search API Multilingual Solr Search integrates with Drupal's standard multilingual features provided by core modules.

As a special feature, Search API Multilingual Solr Search can be configured to deal with the translations of nodes and entities in general on multilingual sites. That means that you can find content in any language, no matter which language was used to enter the search phrase. It's currently a simple implementation of CLIR, but our plan is to extend this feature.

Drupal 7

Drupal 7 is not supported by Search API Multilingual Solr Search. Have a look at Apache Solr Multilingual instead.


Additional Resources

Supporting organizations: 
sponsors development in general.
sponsored Solr 4.x and un-managed schema support.

Project information