Re: noSQL
I'm trying to think of a situation where getting most of the results rather than all would be desirable, but I can't think of one.
I can think of a few (dozen): Google, Facebook, Yelp, Tinder, ... There are many applications where end-users don't need comprehensive or completely correct results. Pretty close is good enough.
Someone else mentions statistical analysis; in general, there are a lot of big-data / OLAP / etc apps where missing the occasional record doesn't hurt.
Before computerization, incomplete results were the norm. Somehow civilization survived.