From: Bryan Green <dbryan.green@gmail.com>
To: Peter Eisentraut <peter@eisentraut.org>
To: pgsql-committers@lists.postgresql.org, Andrew Dunstan <andrew@dunslane.net>
Subject: Re: pgsql: Enable Python Limited API for PL/Python on MSVC
Date: Thu, 15 Jan 2026 10:21:50 -0600
Message-ID: <0de98c41-4145-44c1-aac5-087cf5b3e4a9@gmail.com> (raw)
In-Reply-To: <397fa815-c0cc-4531-9d09-0be3cc72c59a@eisentraut.org>
References: <E1vfxZ0-000P6X-0h@gemulon.postgresql.org>
<397fa815-c0cc-4531-9d09-0be3cc72c59a@eisentraut.org>
On 1/15/2026 3:36 AM, Peter Eisentraut wrote:
> This is failing on buildfarm member drongo: <https://
> buildfarm.postgresql.org/cgi-bin/show_history.pl?nm=drongo&br=master>.
> AFAICT, this is the only buildfarm member that tests Python on Windows,
> so we have no additional results to compare with. It did pass on Cirrus
> CI. Andrew/Bryan, could you figure out how the Python installation on
> drongo is different?
>
Peter, Andrew,
The failure on drongo is due to my writing this patch to support meson
versions >= 1.1.0. I setup my local environment to match CI and was
using meson 1.10.0. Before 1.1.0 you needed to pass the include
directory to check_headers with arg:. I have made the changes and
tested python 3.11 w/meson 0.57.2 and 1.0.1. I have also retested with
python 3.14 and meson 1.10.0. Everything passed.
Additional items to note:
1. meson 1.0.1 expects distutils which was retired in python 3.12. If
you want to use a later python with that version of meson (or earlier)
you will need to install setuptools which has a distutils shim I am led
to believe.
2. when building with meson 0.57.2 I had to provide -Dreadline=disabled
for the build to succeed.
The v2 patch is attached.
--
Bryan Green
EDB: https://www.enterprisedb.comAttachments:v2-0001-Enable-Python-Limited-API-for-PL-Python-on-MSVC.patch (text/plain, 3.0K) download
From a3d39e86c640ef441ac919aefaec6a670beacb0b Mon Sep 17 00:00:00 2001
From: Bryan Green <dbryan.green@gmail.com>
Date: Fri, 2 Jan 2026 10:48:54 -0600
Subject: [PATCH v2] Enable Python Limited API for PL/Python on MSVC
Previously, the Python Limited API was disabled on MSVC due to build
failures caused by Meson not knowing to link against python3.lib
instead of python3XX.lib when using the Limited API.
This commit works around the Meson limitation by explicitly finding
and linking against python3.lib on MSVC, and removes the preprocessor
guard that was disabling the Limited API on MSVC in plpython.h.
This requires python3.lib to be present in the Python installation,
which is included when Python is installed.
Discussion: https://www.postgresql.org/message-id/flat/ee410de1-1e0b-4770-b125-eeefd4726a24%40eisentraut.org
---
meson.build | 21 +++++++++++++++++++--
src/pl/plpython/plpython.h | 4 ----
2 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/meson.build b/meson.buildindex d7c5193d4c..4b45732d53 100644--- a/meson.build+++ b/meson.build@@ -1329,9 +1329,26 @@ if not pyopt.disabled()
pm = import('python')
python3_inst = pm.find_installation(python.full_path(), required: pyopt)
if python3_inst.found()
- python3_dep = python3_inst.dependency(embed: true, required: pyopt)+ # For Limited API on MSVC, link against python3.lib instead of python3XX.lib.+ # Meson doesn't handle this automatically:+ # <https://github.com/mesonbuild/meson/issues/13824>+ if host_system == 'windows' and cc.get_id() == 'msvc'+ python3_prefix = python3_inst.get_variable('prefix')+ python3_libdir = python3_prefix / 'libs'+ python3_incdir = python3_prefix / 'include'+ python3_lib = cc.find_library('python3', dirs: python3_libdir, required: pyopt)+ python3_dep = declare_dependency(+ include_directories: include_directories(python3_incdir),+ dependencies: python3_lib,+ )+ # Explicit args needed for older Meson compatibility+ python3_header_check_args = ['/I' + python3_incdir]+ else+ python3_dep = python3_inst.dependency(embed: true, required: pyopt)+ python3_header_check_args = []+ endif
# Remove this check after we depend on Meson >= 1.1.0
- if not cc.check_header('Python.h', dependencies: python3_dep, required: pyopt, include_directories: postgres_inc)+ if not cc.check_header('Python.h', args: python3_header_check_args, dependencies: python3_dep, required: pyopt, include_directories: postgres_inc)
python3_dep = not_found_dep
endif
endif
diff --git a/src/pl/plpython/plpython.h b/src/pl/plpython/plpython.hindex 118b310084..445f7bc31a 100644--- a/src/pl/plpython/plpython.h+++ b/src/pl/plpython/plpython.h@@ -25,12 +25,8 @@
/*
* Enable Python Limited API
- *- * XXX currently not enabled on MSVC because of build failures
*/
-#if !defined(_MSC_VER)
#define Py_LIMITED_API 0x03020000
-#endif
/*
* Pull in Python headers via a wrapper header, to control the scope of
--
2.52.0.windows.1
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To: pgsql-committers@postgresql.org
Cc: dbryan.green@gmail.com, peter@eisentraut.org, andrew@dunslane.net
Subject: Re: pgsql: Enable Python Limited API for PL/Python on MSVC
In-Reply-To: <0de98c41-4145-44c1-aac5-087cf5b3e4a9@gmail.com>
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