Re: domain cast in parameterized vs. non-parameterized query

You might consider whether you can write 'spa-000'::uid explicitly in your
query; that results in immediate application of the domain coercion, so
that the planner no longer sees that as a run-time operation it has to
avoid.

It's tempting to wonder whether we could somehow constant-fold
CoerceToDomain, at least in the estimation case, but I'm afraid that
would lead to domain constraint failures that would not necessarily occur
at runtime.  Or we could skip the domain check for estimation purposes,
but then we're possibly feeding a value that fails the domain check to a
function that might not work right under such conditions.  So on the
whole I'm afraid to monkey with that decision.