There are hooks for the planner and the executor, so you could force their hand quite easily with a plan extracted from a previous EXPLAIN. Being able to pass a plan at protocol level would be more efficient, for sure. I’ve worked on Postgres-XC and somewhat Postgres-XL, and that’s something that we wanted to do to generate a plan on one node, and push down the compiled plan down to other nodes to avoid the overhead of the plan computation. This stuff did that for snapshots and a few more things with an extension of the protocol.