Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> One approach is to handle the conversion from unknown to the right data
> type transparently in the backend. Attached patch adds a
> coerce-param-hook for fixed params that returns a CoerceViaIO node to
> convert the param to the right type at runtime. That's quite similar to
> the way unknown constants are handled.
The idea of using a coerce_hook instead of inventing several new API
layers is attractive, but have you checked that there are no callers
for which this would be a bad idea?
Another issue is that this fails to mimic the usual varparams behavior
that a Param of unknown type should be resolved to only one type when it
is referenced in multiple places. I'm not sure that that's a critical
behavior, but I'm definitely not sure that it's not.
regards, tom lane