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<chapter id="plpython">

<title>PL/Python - Python Procedural Language</title>

</para>

<para>

On most (possibly all) platforms, it is not possible to use

PL/Python based on Python 2 and PL/Python based on Python 3 in the

same session, because the symbols in the dynamic modules will

clash, which will result in crashes of the PostgreSQL server

process. It is possible, however, to use both PL/Python variants

in the same database, from separate sessions.

It is not allowed to use PL/Python based on Python 2 and PL/Python

based on Python 3 in the same session, because the symbols in the

dynamic modules would clash, which could result in crashes of the

PostgreSQL server process. There is a check that prevents mixing

Python major versions in a session, which will abort the session if

a mismatch is detected. It is possible, however, to use both

PL/Python variants in the same database, from separate sessions.

</para>

</sect1>

staticconstintplpython_python_version=PY_MAJOR_VERSION;

{

staticboolinited= false;

constint**version_ptr;

version_ptr= (constint**)find_rendezvous_variable("plpython_python_version");

if (!(*version_ptr))

*version_ptr=&plpython_python_version;

{

if (**version_ptr!=plpython_python_version)

ereport(FATAL,

(errmsg("Python major version mismatch in session"),

errdetail("This session has previously used Python major version %d, and it is now attempting to use Python major version %d.",

**version_ptr,plpython_python_version),

errhint("Start a new session to use a different Python major version.")));

}

if (inited)

return;