> Concurrent data modifications can cause problems. If somebody inserts a new row to the table while we are watching the first page, it can happen that that row would have shown up on the first page. Now if we fetch the second page, the whole result set will shift by one position, and the second page will start with the last row from the first page.
Even worse, if a concurrent statement deletes a row, it could happen that we skip a row in the result set if we move to page two.Emphasis mine: this happens when trimming my Watch Later list in Youtube Mobile (well, Vanced 17.03.38)