I am looking for an open source search engine plugin written in php for my website(eCommerce). Before anybody answer that I have a doubt regarding the search engine. Usually search engine crawl web pages, create indexes and then use them while looking for contents. But will the same model work for eCommerce websites? Yeah, it can crawl products pages, index them but don't you think it would be better if it crawls the database directly and index the products stored in the database? And when a user search for any product, it will simply give us the rows of the table which matches the user query?

May be what I am asking is a stupid question but I am new to web development, so kindly help me to understand the concept.

I have looked at a search engine called Sphider but didn't get what all I have to do to make it work with an eCommerce website.