With NoSQL becoming all the rage for Web developers who are tired of building complex SQL, will NoSQL databases replace traditional relational databases in PHP development? Probably not, but for those PHP developers who are ready to make the leap, the Redis NoSQL database server provides a powerful and speedy alternative to relational database servers. Redis is similar to Memcached in terms of speed, but the data isn't volatile. That means that when your server reboots, your Redis data will still be there. You can back it up too.
Key-value NoSQL databases like Redis are very appealing, particularly because of their speed, flexibility and scalability. Because Redis is a key-value database not a relational one, you don't have to spend an inordinate amount of time building a SQL schema and worrying about relational stuff such as foreign keys and primary keys. Of course, you still need to design your database, but you don't have to think about whether to use second normal form or third normal form.
In his PHPBuilder.com tutorial, Keith Vance demonstrates how simple building a Web application using PHP and Redis is.