readme.md

Custom Analyzers

By default, the full-text index in Stardog uses Lucene's StandardAnalyzer.

However, any class implementing org.apache.lucene.analysis.Analyzer can be used in place of the default analyzer. To specify a different Analyzer a service named com.complexible.stardog.search.AnalyzerFactory should be registered. AnalyzerFactory returns the desired Analyzer implementation to be used when creating the Lucene index from the RDF contained in the database.

This is an example of an AnalyzerFactory which uses the built-in Lucene analyzer for the French language:

public final class FrenchAnalyzerFactory implements AnalyzerFactory {

	/**
	 * {@inheritDoc}
	 */
	@Override
	public Analyzer get() {
		return new FrenchAnalyzer(Version.LUCENE_47);
	}
}

Any of the common Lucene analyzers can be used as well as any custom implementation of Analyzer. In the latter case, be sure your implementation is in Stardog's class path.

Create a file called com.complexible.stardog.search.AnalyzerFactory in the META-INF/services directory. The contents of this file should be the fully-qualified class name of your AnalyzerFactory. The jar containing this META-INF/services directory as well as the implementation for the class it references is then added on the classpath. Stardog will pick up the implementation on startup by using the JDK ServiceLoader framework.

Note, as of Stardog 3.0, only one AnalyzerFactory can be registered at a time, attempts to register more than one will yield errors on startup.