Re: Error-safe user functions

Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> On 2022-Dec-09, Tom Lane wrote:
>> ...  So I think it might be
>> okay to say "if you want soft error treatment for a domain,
>> make sure its check constraints don't throw errors".

> I think that's fine.  If the user does, say "CHECK (value > 0)" and that
> results in a soft error, that seems to me enough support for now.  If
> they want to do something more elaborate, they can write C functions.
> Maybe eventually we'll want to offer some other mechanism that doesn't
> require C, but let's figure out what the requirements are.  I don't
> think we know that, at this point.

A fallback we can offer to anyone with such a problem is "write a
plpgsql function and wrap the potentially-failing bit in an exception
block".  Then they get to pay the cost of the subtransaction, while
we're not imposing one on everybody else.

                        regards, tom lane