Re: BUG #2811: Error determining param type in prepared statement of unused variable

"Ross Cohen" <rcohen@snurgle.org> writes:
> PREPARE demo (unknown) AS SELECT 1;
> ERROR:  could not determine data type of parameter $1

This doesn't seem like a bug to me.  The parser needs to be able to
resolve the types of any unknown parameters, and you've not given it
enough information to do that.

            regards, tom lane