Then each went to his own home

In my previous article named “Tags: database schemas” we analysed different database schemas on how they could meet the needs of tag systems. In this article, the focus is on performance (speed). That is: if you want to build a tagsystem that performs good with about 1 million items (bookmarks for instance), then you may want to have a look at the following result of my performance tests.
In this article I tested tagging of bookmarks, but as you can tag pretty much anything, this goes for tagging systems in general.

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While setting up the promised performance test in my last post, I did some tests with the MySQL fulltext features and it seems that they are built for tagging systems. Take a look at the queries (if it is not clear for you what is done here, please read my previous post).
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Recently, on del.icio.us mailinglist, I asked the question “Does anyone know the database schema of del.icio.us?” .
I got a few private responses so I wanted to share the knowledge with the world.

The Problem: You want to have a database schema where you can tag a bookmark (or a blog post or whatever) with as many tags as you want. Later then, you want to run queries to constrain the bookmarks to a union or intersection of tags. You also want to exclude (say: minus) some tags from the search result.
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