Re: Getting rid of "unknown error" in dblink and postgres_fdw

On 12/21/2016 08:49 AM, Tom Lane wrote:
> We have a report in pgsql-general of a dblink query failing with
> ERROR: unknown error
> This is, to say the least, unhelpful. And it violates our error
> message style guidelines.
>
> Where that is coming from is a situation where we've failed to extract
> any primary message from a remote error. (I theorize that today's report
> is triggered by an out-of-memory situation, but that's only an unsupported
> guess at the moment.)
>
> I propose that we should change that string to "could not obtain message
> string for error on connection "foo"", or something along that line.
>
> postgres_fdw has the same disease. It wouldn't have the notion of a named
> connection, but maybe we could insert the foreign server name instead.
>
> A possible objection is that if we really are on the hairy edge of OOM,
> trying to construct such error strings might push us over the edge and
> then you get "out of memory" instead. But IMO that's not worse; it
> could be argued to be a more useful description of the problem.
>
> Comments?

Seems reasonable to me. I can work on it if you'd like. Do you think
this should be backpatched?

Joe

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