Maxim Boguk <maxim.boguk@gmail.com> writes:
> And the problem is that the cost of a custom plan ignores the cost of
> planning itself (which is like 2x orders of magnitude worse than the cost
> of real time partition pruning of a generic plan).
False. The estimate is evidently pretty wrong, but it's not that
there is no consideration at all. See around line 1370 in
src/backend/utils/cache/plancache.c.
regards, tom lane