Sphinx search

Sphinx is an open-source full-text search server, designed from the ground up with performance, relevance (aka search quality), and integration simplicity in mind.  Sphinx lets you either batch index and search data stored in an SQL database, NoSQL storage, or just files quickly and easily — or index and search data on the fly, working with Sphinx pretty much as a database server.  A variety of text processing features enable fine-tuning Sphinx for your particular application requirements, and a number of relevance functions ensures you can tweak search quality as well.