We have a complex query with OPTION(user_estimates='on') at the end. And we have two estimates in that query with 0 percent. It worked perfectly for a few months (although the docs say not to use 0 percent) but today suddenly the optimizer started to choose wrong execution plan (i. e. ignored these estimates). Then I changed these estimates to 0.00001 percent, and everything works perfectly again. So the question is: what is the least value for user estimates that is safe to use in terms of forcing optimizer to start scanning from concrete index? How much differently does the optimizer interpret 0 and 0.00001 (or even less) percent? Thanks.