In his continuing look at using CouchDb as a file system, Gonzalo Ayuso has posted this third part in the group of articles about using streams to connect your scripts to the database instance.
I'm still working in my filesystem with CouchDb. After creating a library to enable working with PHP and CouchDB (see the post here), and after using Monkey Patching to override standard PHP's filesystem functions. I've created another solution now. Thanks to a comment in my last post (many thanks Benjamin) I've discovered that it's possible to create a stream wrapper in PHP (I thought it was only available with a C extension).
He includes the code for the stream connection wrapper, a pretty simple script that parses the string it's given and opens a read/write stream to the source. There's also a "url_stat" method that will return to you the size of the stream in bytes. Then you just register the wrapper and go about your normal file system calls to use the CouchDb directly.