Pickles aren’t really rotten. Sour pickles are brined in salt water brine at about 70 degrees F for about 5 days. Dill pickles that are traditionally bought in jars in the grocery store are hot water canned in vinegar brine and are ready in just a couple days.
They consider fermentation in this article as a form of rotting. Most pickles that aren’t mass produced are in fact fermented. The salt is used as a selective media for the right acidic organisms to grow in. So if it’s not a mass produced pickle and it’s barrel aged, like classic sour or kosher pickles, it is fermented.