Re: Resolving the python 2 -> python 3 mess

Noah Misch <noah(at)leadboat(dot)com> writes:
> On Wed, Feb 19, 2020 at 08:42:36PM +0100, Peter Eisentraut wrote:
>> I think there should just
>> be an option "plpython is: {2|3|don't build it at all}". Then packagers can
>> match this to what their plan for /usr/bin/python* is -- which appears to be
>> different everywhere.

> Today, we do not give packagers this sort of discretion over SQL-level
> behavior. We formerly had --disable-integer-datetimes, but I view that as the
> lesser of two evils, the greater of which would have been to force dump/reload
> of terabyte-scale clusters. We should continue to follow today's principle,
> which entails not inviting packagers to align the nature of "LANGUAGE
> plpythonu" with the nature of /usr/bin/python.

FWIW, I've abandoned this patch. We've concluded (by default, at least)
that nothing is getting done in v13, and by the time v14 is out it will
be too late to have any useful effect. I expect that the situation
on-the-ground by 2021 will be that packagers build with PYTHON=python3
and package whatever they get from that. That means (1) plpythonu won't
exist anymore and (2) users will be left to their own devices to convert
existing plpython code. Now, (1) corresponds to not providing any
/usr/bin/python executable, only python3 -- and that is a really common
choice for distros to make, AFAIK, so I don't feel too awful about it.
I find (2) less than ideal, but there's evidently not enough interest
in doing anything about it. There's certainly going to be no point in
shipping a solution for (2) if we fail to do so before v14; people
will already have done the work by hand.

We should, however, consider updating the plpython docs to reflect
current reality. Notably, the existing wording in section 45.1
suggests that we'll eventually redefine "plpythonu" as Python 3,
and it seems to me that that's not going to happen.

regards, tom lane