Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> While working on the grouping sets patches for queries with GROUP BY
> items that are constants, I noticed $subject on master. As an
> example, consider
This particular example seems like it's just an illustration of
our known bugs with grouping sets using non-Var columns. I see
no reason to blame the plan cache for it. Do you have any
examples that don't depend on such a bug?
(And yes, I apologize for not yet having reviewed your patch
to fix the grouping-sets bug.)
regards, tom lane