Re: [HACKERS] GSOC'17 project introduction: Parallel COPY executionwith errors handling

On 1/22/18 21:33, Craig Ringer wrote:
> We don't have much in the way of rules about what input functions can or
> cannot do, so you can't assume much about their behaviour and what must
> / must not be cleaned up. Nor can you just reset the state in a heavy
> handed manner like (say) plpgsql does.

I think one thing to try would to define a special kind of exception
that can safely be caught and ignored.  Then, input functions can
communicate benign parse errors by doing their own cleanup first, then
throwing this exception, and then the COPY subsystem can deal with it.