PHP: What are the currently used Column Oriented Databases

What are the currently used Column Based Databases that w开发者_JAVA技巧ork with PHP? and are any of them free?

I think you want to know about NoSQL databases and not Column Oriented DBs.

Both are often called as the NoSQL databases, most of the implementations are free but the most popular in the PHP community must be MongoDB.

There is a rather large list of Column Oriented Databases at Wikipedia. I know that at least Infobright offers a Community Edition of their product and it works with MySql. There was a webinar recently at Zend as well.