Re: Misleading error message in logical decoding for binary plugins

On 2014-09-03 09:36:32 -0400, Robert Haas wrote:
> On Fri, Aug 29, 2014 at 9:48 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> > On 2014-08-29 22:42:46 +0900, Michael Paquier wrote:
> >> Hi all,
> >>
> >> Using a plugin producing binary output, I came across this error:
> >> =# select data from pg_logical_slot_peek_changes('foo', NULL, NULL);
> >> ERROR: 0A000: output plugin cannot produce binary output
> >> LOCATION: pg_logical_slot_get_changes_guts, logicalfuncs.c:404
> >>
> >> Shouldn't the error message be here something like "binary output plugin
> >> cannot produce textual output"? The plugin used in my case produces binary
> >> output, but what is requested from it with pg_logical_slot_peek_changes is
> >> textual output.
> >
> > I don't like the new message much. It's imo even more misleading than
> > the old message. How about
> > "output pluing produces binary output but the sink only accepts textual data"?
>
> Maybe:
>
> ERROR: pg_logical_slot_peek_changes cannot be used with a plugin that
> produces only binary output
> HINT: Use pg_logical_slot_peek_binary_changes instead.

That level has no knowledge of what it's used by, so I think that'd
require bigger changes than worth it.

Greetings,

Andres Freund

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Andres Freund http://www.2ndQuadrant.com/
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