Re: Error-safe user functions

Hi,

On 2022-12-11 12:24:11 -0500, Tom Lane wrote:
> Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> > On 2022-12-10 Sa 14:38, Tom Lane wrote:
> >> I have not done anything here about errors within JsonbValueToJsonb.
> >> There would need to be another round of API-extension in that area
> >> if we want to be able to trap its errors. As you say, those are mostly
> >> about exceeding implementation size limits, so I suppose one could argue
> >> that they are not so different from palloc failure. It's still annoying.
> >> If people are good with the changes attached, I might take a look at
> >> that.
>
> > Awesome.
>
> I spent some time looking at this, and was discouraged to conclude
> that the notational mess would probably be substantially out of
> proportion to the value. The main problem is that we'd have to change
> the API of pushJsonbValue, which has more than 150 call sites, most
> of which would need to grow a new test for failure return. Maybe
> somebody will feel like tackling that at some point, but not me today.

Could we address this more minimally by putting the error state into the
JsonbParseState and add a check for that error state to convertToJsonb() or
such (by passing in the JsonbParseState)? We'd need to return immediately in
pushJsonbValue() if there's already an error, but that that's not too bad.

Greetings,

Andres Freund