Re: Bypassing shared_buffers

Vladimir Churyukin <vladimir@churyukin.com> writes:
> 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?

It's a complete non-starter.  Pages on disk are not necessarily up to
date; but what is in shared buffers is.

            regards, tom lane