The package to install is postgresql-plpython3.
By way of dependencies, this will install postgresql-plpython3-9.1, which provides these files:
$ dpkg -L postgresql-plpython3-9.1
/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/postgresql-plpython3-9.1
/usr/share/doc/postgresql-plpython3-9.1/copyright
/usr/share/postgresql
/usr/share/postgresql/9.1
/usr/share/postgresql/9.1/extension
/usr/share/postgresql/9.1/extension/plpython3u--1.0.sql
/usr/share/postgresql/9.1/extension/plpython3u.control
/usr/share/postgresql/9.1/extension/plpython3u--unpackaged--1.0.sql
/usr/lib
/usr/lib/postgresql
/usr/lib/postgresql/9.1
/usr/lib/postgresql/9.1/lib
/usr/lib/postgresql/9.1/lib/plpython3.so
/usr/share/doc/postgresql-plpython3-9.1/changelog.Debian.gz
and then you can do:
postgres=# create extension plpython3u;
CREATE EXTENSION
Dunno if it was true when you wrote your question, but the puppetlabs/postgresql module does some pretty clever stuff with versions that are not standard for your OS distro, including installing the required repository.
Snippets from my config:
In one of my puppet classes I call:
class { 'postgresql::globals':
encoding => hiera('postgresql::globals::encoding', 'UTF8'),
locale => hiera('postgresql::globals::locale', 'C'),
manage_package_repo => hiera('postgresql::globals::manage_package_repo', false),
version => hiera('postgresql::globals::version', undef),
notify => Class['postgresql::server', 'postgresql::client'],
}
and in my hiera config data I have:
postgresql::globals::version: "9.3"
postgresql::globals::manage_package_repo: true
Using hiera like this is optional of course, but it gives you a nice way to use different versions on different hosts. On later versions of puppet (at least 3.x) you can override postgresql::globals variables without needing that to be part of how you call the package.
You won't need to do stuff from source here, but if you did, I'd recommend that you should build your own package rather than try to automate the build process through puppet. Avoid it as far as possible though, since it sets you up to do ongoing maintenance of that package.
Best Answer
Yes, the PGSQL system user (usually postgres) has its home directory set to /var/lib/postgresql. I'm presuming you installed your database in a different location. Since that directory doesn't exist, the PSQL program cannot access that folder to create its history file. (PSQL is the interactive command line for PGSQL).
Honestly, it's not that big of a deal. That history file is just a list of commands that were executed inside the PSQL interface.
Since you're done installing, I doubt you'll ever see the message again. That is, unless you connect to PSQL using your own account and you continue to get a similar error message. In that case, your HOME variable might be wrong. You're not logged in to your system as postgres are you? If you are planning on using that user interactively (not advised at all), then you'll have to set its HOME directory to some valid folder.
Here are some reference solutions.