Commits
David Li authored and Antoine Pitrou committed da401241027
ARROW-13574: [C++] Add 'count all' option to count kernels Pandas calls this 'size'. I opted not to extend ScalarAggregateOptions as the option wouldn't apply to any other kernel. Closes #10895 from lidavidm/arrow-13574 Authored-by: David Li <li.davidm96@gmail.com> Signed-off-by: Antoine Pitrou <antoine@python.org>