Got to scratch of one of three remaining old (14years and counting) design mistakes this week.

Together with a colleague we replaced a 1.5 billion row table that I out of ignorance then designed with a 3 column composite primary key instead of an identity column.

Moving the data while keeping all synchronized (the table gets up towards 2 million new rows and 2 million updates a day while constantly being queried) took 1 week.

Just 2 skeletons left to clean out, any year now ;).