How to index .doc and .pdf files stored in a database (using MS SQL Server) in asp.net (C #)?
You need to read Full Text Search and iFilter - here are the MSDN docs for IFilter . Looks like there is even an IFilter MSDN blog .
This site looks like this: a good list of filters that you can download .
You can check this this and this .
Txt Link: http://www.codeproject.com/KB/IP/Searcharoo_4.aspx
Txt Link: http://www.searcharoo.net/
Lucene.net is another well-supported option. It is also open source.