How to search for text fragments in a database

Question

Are there any open source or commercial tools available that allow for text fragment indexing of database contents and can be queried from Java?

Background of the questi

Answer 1

Shingle search could do the trick.

http://en.wikipedia.org/wiki/W-shingling

For example, if you use 3-character shingles, you can split "Roisonic" to: "roi", "son", "ic ", and store all three values, associating them with original entry. When searching for "oison", you first will search for "ois", "iso", "son". First you fuzzy-match all entries by shingles (finding the one with "son"), and then you can refine the search by using exact string matching.

Note that 3-character shingle require the fragment in query to be at least 5 characters long, 4-char shingle requires 7-char query and so on.