"Simple" sharding tutorials using MySQL or PostgreSQL?
subwindow: When I've planned out sharded infrastructures, the database usually wasn't that big of a concern.  The web framework or system architecture are usually the pain point. And with Rails, you have to abuse establish_connection if you're going to have each web head read from multiple shards.The easiest route I've gone when setting up a sharded infrastructure is to use subdomains and a 1-1 Web:DB setup.  Have each subdomain go (either thru a reverse proxy or hardware load balancer) to a different (sharded) webhead.  Each web head talks to two databases- the common database and its sharded DB.  With this you'll probably want a "common" web head to handle home page traffic and authentication (after they are authenticated they'd get dished off to their shard).Salesforce.com was my inspiration for this method, and it is probably reasonably common.  It probably also has a name, but I do not know what it is.