Questions for 6.S897 lecture 20 (Serving Systems, 12/3). Email your answers to 6.s897staff@gmail.com. 1) How are posting lists divided across nodes in Unicorn? 2) Why is it sometimes more efficient to use the apply operator in Unicorn than to have the client issue two queries? 3) What happens if a real-time node fails in Druid? What if it was in the middle of doing a handoff?