Re: pg_upgrade Python version issue on openSUSE

On 9/26/20 7:49 AM, Tom Lane wrote:
> =?utf-8?Q?Paul_F=C3=B6rster?= <paul.foerster@gmail.com> writes:
>> On 26. Sep, 2020, at 16:07, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> However, I don't understand how "drop extension plpythonu"
>>> worked for you, given your previous query showing that
>>> that extension wasn't installed.
> 
>> just checked with another 12.4. It's the same:
> 
>> postgres=# select * from pg_available_extension_versions where installed;
>>    name   | version | installed | superuser | relocatable |   schema   | requires |
comment
>>
---------+---------+-----------+-----------+-------------+------------+----------+--------------------------------------------------------------
>>   plperlu | 1.0     | t         | t         | f           | pg_catalog |          | PL/PerlU untrusted procedural
language
>>   dblink  | 1.2     | t         | t         | t           |            |          | connect to other PostgreSQL
databasesfrom within a database
 
>>   plpgsql | 1.0     | t         | f         | f           | pg_catalog |          | PL/pgSQL procedural language
>>   plperl  | 1.0     | t         | f         | f           | pg_catalog |          | PL/Perl procedural language
>> (4 rows)
> 
>> postgres=# drop extension plpythonu ;
>> DROP EXTENSION
>> postgres=# create extension plpython3u ;
>> CREATE EXTENSION
> 
> Actually, now that I think about it, you're querying the wrong view.
> I'm too lazy to check the source code right now, but I'm pretty sure
> that pg_available_extension_versions is mostly driven off what control
> files exist in the on-disk libdir.  But that may have little to do with
> what's in the system catalogs.  You should have checked pg_extension,
> or just "\dx" in psql.

I believe the issue is here:

select * from pg_pltemplate ;


  plpythonu  | f           | f             | plpython_call_handler  | 
plpython_inline_handler  | plpython_validator  | $libdir/plpython2 | NULL
  plpython2u | f           | f             | plpython2_call_handler | 
plpython2_inline_handler | plpython2_validator | $libdir/plpython2 | NULL
  plpython3u | f           | f             | plpython3_call_handler | 
plpython3_inline_handler | plpython3_validator | $libdir/plpython3 | NULL


The default plpython is plpythonu and that points at $libdir/plpython2.

The instructions here:

https://www.postgresql.org/docs/12/plpython-python23.html

offer a work around:

"Daredevils, who want to build a Python-3-only operating system 
environment, can change the contents of pg_pltemplate to make plpythonu 
be equivalent to plpython3u, keeping in mind that this would make their 
installation incompatible with most of the rest of the world."


> 
>             regards, tom lane
> 
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com