A database specialist and blogger I follow came across this post:
http://stackoverflow.com/questions/888224/what-is-your-longest-held-programming-assumption-that-turned-out-to-be-incorrect
which got me wondering, what assumptions have I made that turned out to be incorrect? The one that came to mind for me was the idea that going to the database is slower than pulling in all the data you need at once and querying the stored data when necessary. It really depends on your situation. When you don't have to deal with remoting or firewalls, it is very often faster to query the database than to use a stored list.
More importantly, though, this question should make everyone ask themselves: what assumptions do I make today that are based on incomplete, out-dated, or inaccurate information? A post like this one is good in that it helps everyone to see what assumptions had been proved false and allows all the posters and readers to learn from others' mistakes. However, the goal should be to question our current assumptions, not just take pride in previous lessons learned. Looking back is certainly a valuable exercise, but looking for new lessons to be learned is more important.
