Here's a thought question for today: why can't database tables index themselves?
Obviously, indexes are a central concept to databases and database performance. But horror tales still abound of naive developers who "forget" to index their tables, and encounter massive performance and scalability problems down the road as their tables grow. I've run into it personally, and I've read plenty of other sad tales of woe from other developers who have, too. I've also forgotten to build indexes myself on non primary key columns many times. Why aren't databases smart enough to automatically protect themselves from this?
This is a companion discussion topic for the original blog entry at: http://www.codinghorror.com/blog/2006/07/why-cant-database-tables-index-themselves.html