»lucene«

With Helma, i am using the Java Lucene to implement fulltext search. In the Ruby world there is Ferret. It's nearly the same as Lucene - great!
Acts as Ferret integrates it in RoR.

For the quickest introduction:

• a perfect slideshow
• best tutorial for acts_as_ferret
• another tutorial for acts on ferret
• introduction ferret in general

To include german stemming do this.

Some troubleshooting if this doesn't work.

This configuration worked for me:
acts_as_ferret(
{ :fields => {
:fieldname1 =>{},
:fieldname2 =>{}
}
},
:analyzer => GermanStemmingAnalyzer.new
)

To get informations about the current index for a Model:

>> puts [Modelname].aaf_index.to_yaml
or
>> puts [Modelname].aaf_configuration.to_yaml