To be clear, I'm talking about bypassing shared buffers for reading data / indexes only, not about disabling it completely (which I guess is impossible anyway).
There is often a need to test particular queries executed in the worst-case scenario, i.e. right after a server restart or with no or minimal amount of data in shared buffers. In Postgres it's currently hard to achieve (other than to restart the server completely to run a single query, which is not practical). Is there a simple way to introduce a GUC variable that makes queries bypass shared_buffers and always read from storage? It would make testing like that orders of magnitude simpler. I mean, are there serious technical obstacles or any other objections to that idea in principle?