Re: proposal: PL/Pythonu - function ereport

On 2/4/16 3:13 AM, Catalin Iacob wrote:

Thanks for the overview. Very helpful.

> I find existing behaviour for 2, 3 and 4 unlike other Python APIs I've
> seen, surprising and not very useful. If I want to log a tuple I can
> construct and pass a single tuple, I don't see why plpy.info() needs
> to construct it for me. And for the documented, single argument call
> nothing changes.

Agreed, that usage is wonky.

> The question to Bruce (and others) is: is it ok to change to the new
> behaviour illustrated and change meaning for usages like 2, 3 and 4?

If any users have a bunch of code that depends on the old behavior,
they're going to be rather irritated if we break it. If we want to
depricate it then I think we need a GUC that allows you to get the old
behavior back.

> If we don't want that, the solution Pavel and I see is introducing a
> parallel API named plpy.raise_info or plpy.rich_info or something like
> that with the new behaviour and leave the existing functions
> unchanged. Another option is some compatibility GUC but I don't think
> it's worth the trouble and confusion.

If we're going to provide an alternative API, I'd just do
plpy.raise(LEVEL, ...).

At this point, my vote would be:

Add a plpython.ereport_mode GUC that has 3 settings: current
(deprecated) behavior, allow ONLY 1 argument, new behavior. The reason
for the 1 argument option is it makes it much easier to find code that's
still using the old behavior. I think it's also worth having
plpy.raise(LEVEL, ...) as an alternative.

If folks feel that's overkill then I'd vote to leave the existing
behavior alone and just add plpy.raise(LEVEL, ...).
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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