Solr

By introducing stemming the search results were already improved a lot. But there is one speciality in the so called Germanic languages such as German, which prevents the results from being as fine as with English: It's creation of compound words.

One example: The English word Danubian steam ship becomes in German Donaudampfschiff.

Apachesolr is a awesome search machine. I like a lot the facetted search that comes with Apachesolr on Drupal.

But there is one drawback in the current module: it is optimized for the English language. That means that all the text analysis that is done when building up the search index or when performing a search query is based on English.