web:config

Now for something technical, unrelated to web dev and Opera…
I joined my company in March 2007, and since then I've worked mostly in Oracle. Back then, I only had a theoretical knowledge of databases, but meanwhile I learned a lot in most areas, and now I'll fairly comfortable working with a big database.
In many technologies you’ll always find fun stuff to do. So know I post you a contest:
Which is the smallest possible query you can write, that'll take the longest to execute?
This is solely an exercise. I won't buy you a pack of peanuts if you beat everyone else to the answer.
Some notes:

• it may work only in a specific database
• you can only use builtin functions, if any, not custom ones.
• your answer must be solely a SQL query, the name of the database the query runs and an explanation of how it works.
• doing wild Cartesian merges is not the answer, like

  select 1 from dba_objects, dba_objects, dba_objects, dba_objects, dba_objects, ...

  for Oracle. When you find that the query takes an eternity to execute, you can still add another dba_objects to the FROM clause and you’ll go beyond eternity, while making the query fatter and therefore beating the prime purpose: to be the smallest

Good luck! The challenge is on.

P.S.: Yes, I have a possible answer and I think I already gave enough hints