Basically code noise is anything that pulls your attention away from what the code is supposed to be doing, or obscures the true nature of the code in some way. It’s not something we consider enough when writing T-SQL code, but I think there is a lot to be said for writing code the next person will be able to read.
As a small example, I was debugging something recently and found that all of the insert statements had
ORDER BYclauses. I couldn’t work out why these were making me so angry, after all it’s not doing anything to hurt performance, and in fact isn’t doing anything at all, until one of the other devs in the office pointed out that it’s one example of the code noise that the whole code base is filled with.
Chris provides us a couple examples of noise. My bottom line on this is, develop to the minimum required standards of what the computer needs (i.e., accurate data, fast enough, etc.) and give the humans maintaining the code a fighting chance. Spend more time making it easy for humans and make everybody’s life easier.