What is the difference between EdgeNGramTokenizerFactory EdgeNGramFilterFactory in SOLR?

Question

What is the difference between these two filters? They seem to have the same effect?

Can anyone supply an example of how they are applied to some text?

Thanks

Answer 1

Well, the first provides a Tokenizer, the second provides a Filter ;-)

Since you can have only one Tokenizer, EdgeNGramTokenizerFactory is only useful for fields containing a single word. If you want to separate the string you provide for your documents into words, you'll need a different Tokenizer first, which splits on whitespace or something, and the EdgeNGramFilterFactory afterwards.