ERROR: could not access file “$libdir/plpython2” – ERROR: could not access file “$libdir/plpython3”

Above error described on PG mailing as it failes to CREATE LANGUAGE plpython2u/plpython3u on PG9.3Beta.

Error:
postgres=# create language plpython3u;
ERROR: could not access file "$libdir/plpython3": No such file or directory

postgres=# create language plpython2u;
ERROR: could not access file "$libdir/plpython2": No such file or directory

Before doing some study on above errors I read below PG documentation link on how PostgreSQL permits to create langage plpython and how they should be configured.

http://www.postgresql.org/docs/9.3/static/plpython-python23.html

Its clear from above link you need to compile the binary two time if you need both plpython2u & plpython3u. AFAIK, ActivePython 2.7.x for plpython2u and 3.2.x for plpython3u can be configured on PG 9.2.x without any difficulty, but I not ever gave a try on PG 9.3Beta2. So, considered to give a try and analyze the error about why and how it could be repaired, I first, begun source installation by setting base path with ActivePython 3.2. (ActivePython download link http://www.activestate.com/activepython/downloads)

[root@localhost postgresql-9.3beta1]# export PATH=/opt/ActivePython-3.2/bin:$PATH
[root@localhost postgresql-9.3beta1]# ./configure --prefix=/usr/local/pg93b --with-python

Compilation has failed and showed error in Config.log file as:

make[3]: Entering directory `/usr/local/src/postgresql-9.3beta1/src/pl/plpython'
*** Cannot build PL/Python because libpython is not a shared library.
*** You might have to rebuild your Python installation. Refer to
make[3]: Leaving directory `/usr/local/src/postgresql-9.3beta1/src/pl/plpython'

In PG documentation we have clear directions on the above error and why it happen, plpython will be a shared library on most of the platforms, but on some platforms we need to specifically force the compiler as python from shared library. For that either you can proceed to /src/pl/python/Makefile for changes or specifically state “shared_libpython=yes” while compiling.

Source compilation examines for two files when you use –with-python that are “python” & “python-config”. Although I have ActivePython-3.2 in my base path, still compiler fails to find them “python” & “python-conifg”

[root@localhost postgresql-9.3beta1]# which python
/usr/local/bin/python
[root@localhost postgresql-9.3beta1]# which python-config
/usr/local/bin/python-config

Its because, in ActivePython 3.2 file names will be, “python” as “python3” and “python-config” as “python3-config” therefore compiler pointed to old one instead to new. At this point, Asif Naeem (Thank you for your insight) from our core Dev. Team notfied me to mock existing ActivePython-3.2 files as python & python-config. Its nearly like a hack from him, so I duplicated those files as:

cd /opt/ActivePython-3.2/bin
cp python3-config python-config 
cp python3 python

Ok, now I can see that in my base path.

[root@localhost postgresql-9.3beta1]# export PATH=/opt/ActivePython-3.2/bin:$PATH
[root@localhost postgresql-9.3beta1]# which python 
/opt/ActivePython-3.2/bin/python
[root@localhost postgresql-9.3beta1]# which python-config
/opt/ActivePython-3.2/bin/python-config

I recompiled PG source using –with-python after the alterations and also forcing the compiler to choose SHARED_LIBPYTHON using “shared_libpython”.

./configure --prefix=/usr/local/pg93b3 --with-python
make shared_libpython=yes
make shared_libpython=yes install

These steps will effectively compile PG9.3Beta with ActivePython-3.2 libraries. Now lets create language plpython3u:

-bash-4.1$ psql -p 4444
psql (9.3beta1)
Type "help" for help.

postgres=# create language plpython3u;
The connection to the server was lost. Attempting reset: Failed.
!>
!>

Oops, this is strange, why it has crashed now.. In this kind of situation $PGDATA/pg_log are your friends to insight about the issue. Here’s the database server log information about crash:

2013-07-13 22:08:37 IST-31208-postgres-postgres :LOG: statement: create language plpython3u;
Could not find platform independent libraries 
Could not find platform dependent libraries 
Consider setting $PYTHONHOME to [:]
Fatal Python error: Py_Initialize: Unable to get the locale encoding

Ok. I missed to set python paths, this is very important when you are working with python or perl languages on your database.
I have set PYTHONHOME, PYTHONPATH & LD_LIBRARY_PATH before starting the cluster.

export PYTHONHOME=/opt/ActivePython-3.2/
export PYTHONPATH=/opt/ActivePython-3.2/bin:$PATH
export LD_LIBRARY_PATH=/opt/ActivePython-3.2/lib:$LD_LIBRARY_PATH

/usr/local/pg93b3/bin/pg_ctl -D /usr/local/pg93b3/data/ start

-bash-4.1$ psql -p 4444
psql (9.3beta1)

Type "help" for help.

postgres=# create language plpython3u;
CREATE LANGUAGE

Nice…It has created plpython3u with ActivePython-3.2.

If you want plpython2u also on the same installation. Don’t tweak as we did for ActivePython-3.2, just have a copy of ActivePython-2.7 and set it in the base path and recompile the source.

export PATH=/opt/ActivePython-2.7/bin:$PATH
./configure --prefix=/usr/local/pg93b2 --with-python
make shared_libpython=yes
make shared_libpython=yes install


export PYTHONHOME=/opt/ActivePython-2.7/
export PYTHONPATH=/opt/ActivePython-2.7/bin:$PATH
export LD_LIBRARY_PATH=/usr/local/pg93b2/lib
export LD_LIBRARY_PATH=/opt/ActivePython-2.7/lib:$LD_LIBRARY_PATH

-bash-4.1$ ./psql -p 4444
psql (9.3beta2)
Type "help" for help.

postgres=#
postgres=# create language plpython2u;
CREATE LANGUAGE

Comments & Corrections are most welcomed.

–Raghav