Rachel by the Bay:
There’s a post going around tonight about how someone forgot to put an index on some database thing and wound up doing full table scans (or something like that). The rub is that instead of just being slow, it also cost a fair amount of money because this crazy vendor system charged by the row or somesuch. So, by scanning the whole table, they touched all of those rows, and oh hey, massive amounts of money just set ablaze!
The usual venues are discussing it, and I get the impression some people have the wrong approach to this. I want to describe a truly bad database schema I encountered, and then tell you a little about what it did to the system performance.
A fun story with an excellent twist at the end.