Re: [HACKERS] Couple of issues with prepared FETCH commands

Robert Haas <robertmhaas@gmail.com> writes:
> On Tue, Jan 10, 2017 at 5:38 PM, Andrew Gierth
> <andrew@tao11.riddles.org.uk> wrote:
>> But the problem that actually came up is this: if you do the PQprepare
>> before the named cursor has actually been opened, then everything works
>> _up until_ the first event, such as a change to search_path, that forces
>> a revalidation; and at that point it fails with the "must not change
>> result type" error _even if_ the cursor always has exactly the same
>> result type.  This happens because the initial prepare actually stored
>> NULL for plansource->resultDesc, since the cursor name wasn't found,
>> while on the revalidate, when the cursor obviously does exist, it gets
>> the actual result type.
>> 
>> It seems a bit of a "gotcha" to have it fail in this case when the
>> result type isn't actually being checked in other cases.

> To me, that sounds like a bug.

Yeah --- specifically, I wonder why we allow the reference to an
unrecognized cursor name to succeed.  Or were you defining the bug
differently?
        regards, tom lane