Sorry just to be clear, this is only about the output of a cell? I.e. if I have
df = CSV.read(myhugefile.csv, DataFrame)
data = df[1:10, 1:5]
df = nothing
in a cell then there would not be a reference to the full data read in from csv?
EDIT: I should probably just check this myself but unfortunately my computer is currently unusable due to processing some large csv files in a Jupyter notebook 