  Memory disaggregation (MD) allows for scalable and elastic data center design
by separating compute (CPU) from memory. With MD, compute and memory are no
longer coupled into the same server box. Instead, they are connected to each
other via ultra-fast networking such as RDMA. MD can bring many advantages,
e.g., higher memory utilization, better independent scaling (of compute and
memory), and lower cost of ownership. This paper makes the case that MD can
fuel the next wave of innovation on database systems. We observe that MD
revives the great debate of "shared what" in the database community. We
envision that distributed shared-memory databases (DSM-DB, for short) - that
have not received much attention before - can be promising in the future with
MD. We present a list of challenges and opportunities that can inspire next
steps in system design making the case for DSM-DB.
