Implementing Tags in a Database??

I was considering why del.icio.us doesn’t offer a cloud for tag based queries, while it does offer the cloud for User based queries, and I received the reply that it was (probably) related to query cost, which set me thinking. What would the del.icio.us database look like? The rest of this blog article looks at how one might model the bookmarks and give a clue as to how one might implement it. …