On Wed, Jan 11, 2017 at 11:28 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Tue, Jan 10, 2017 at 5:38 PM, Andrew Gierth >> <and...@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?
I'm not sure whether that's a bug or not. What I was defining as a bug is calling a change from "we don't know what the result type will be" to "we know that the result type will be X" as a change in the result type. That's really totally inaccurate. I've never really understood errors about changing the result type. As a user, I assumed those were unavoidable implementation artifacts, on the theory that they were annoying and therefore the developers would have eliminated such messages had it been practical. As a developer, I've never gotten around to understanding whether that theory was correct. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
