I've been tasked with adding text searching through documents to our application. Since we need to support multiple databases, I didn't want to use the native DBMS indexing options. Looking around, I came across Lucene.Net. It is an open source port of the Java version of Lucene, which is a lightning fast search engine over indexes of documents. The list of features is rather extensive, but my favorite feature would be the advanced search capabilities, including proximity search. There is also a very impressive open source project based on Lucene.Net called SeekAFile which adds functionality over Lucene.Net, and works extremely well, too.

I wanted to centralize the index storage of Lucene.Net, though, since it would be possible to have multiple app servers located in different physical locations, and allowing access from one machine to another could prove problematic. This meant that storing the index to the central database. I found a source code sample that would do this on a Firebird database. I have now converted that to work with MSSQL and Oracle, and it works very well. Yes, it's a bit slower than using the native file system directory provided with Lucene.Net, but it solves the problem we set out to solve.