That looks to be old K&T with a pigtail and some kind of terminal block or something similar??? Kind of hard to tell. Actually "pigtails" are an approved method of wiring up barns and the like up here where there is the risk that the lamp may get bumped. It allows for the lamp and holder to simply move about freely and not get smashed off the ceiling as it would if fastened securely, Mind you there is NO open wiring, and the connections are done in a box and covered with an actual bakelite canopy cover. A.D
That's common in old barns too. They used to run cleat or knob wire the length of the stalls and just pigtail a socket on it wherever one was needed. Cleats seem to be more common with exposed wire. The switch was near the door adn turned them all on at once. If they were real fancy, they used cleats or rosettes and hung a corded socket with a turn switch or pullchain.
I've also heard the term "open or cleat wiring" or "mill wiring".
It must be somewhat safe because I've seen a few systems like this still in operation after 70 or 80 years.