Re: PG20 Minimum Dependency Thread

On Thu Jun 18, 2026 at 6:35 PM CDT, Tom Lane wrote:
> I wrote:
>> Now maybe we can finesse that, like "you can build PL/Python and
>> associated contrib modules with Python >= X, but if you want to
>> run these optional tests, they require Python >= Y". Not sure
>> how comfortable I am with that. I definitely don't want to get
>> into a situation where we require buildfarm owners to have
>> Python >= Y installed, because then we will not have any testing
>> that proves we didn't break the other part. (So we'd need a
>> runtime check to skip these tests on too-old Python.)
>
> Granting that our pytest framework should silently give up if
> Python is too old, the decision of which minimum version to target
> is really kind of independent of what PL/Python does. It becomes
> a tradeoff of ease of coding versus "how many platforms do you want
> this test to be able to run on?". I have no insight on what the
> coding benefits are of different Python versions, but I do have
> this freshly-scraped data about how many buildfarm members are
> reporting which major Python version:
>
> 3 3.5
> 39 3.6
> 5 3.7
> 5 3.8
> 39 3.9
> 6 3.10
> 21 3.11
> 45 3.12
> 48 3.13
> 12 3.14
> 2 3.15
>
> Just eyeing that, it seems like 3.9 or 3.11 would be choices that
> still allow most animals to run the tests.

The latest versions of pytest require Python >= 3.10. In theory, we
could pin to an older pytest version.

For what it's worth, the latest version of Meson supports Python >=
3.7. I wonder if we should tie our Meson and pytest versions together
such that they support the same Python version.

--
Tristan Partin
PostgreSQL Contributors Team
AWS (https://aws.amazon.com)