Horton

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

Joe Conway <mail@joeconway.com>

View thread View on postgr.es
From: Joe Conway <mail@joeconway.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgreSQL.org
Date: 2016-12-21T17:22:25Z
Lists: pgsql-hackers 
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


-- 
Crunchy Data - http://crunchydata.com
PostgreSQL Support for Secure Enterprises
Consulting, Training, & Open Source Development

Commits

  1. Make dblink try harder to form useful error messages

  2. Improve dblink error message when remote does not provide it