Calvin's

In my previous post, I explained how we can run postgresql92 and postgresql91 concurrently.  However, that post does not explain how we can ensure that the psycopg2 we install in our project’s python virtual environment will build against postgresql92 server.

When psycopg2 is installed (via `pip install psycopg2` for instance), psycopg2 depends on the presence of `pg_config` to locate the currently active postgresql version.

If we do `pg_config –sharedir`, we will see

calvin$ pg_config --sharedir
/opt/local/share/postgresql91

which tells us that if we run `pip install virtualenv`, we will essentially be building psycopg2 against postgresql91.

Fortunately for us, using macports, it’s trivial and completely painless to switch our postgresql server version.

calvin$ sudo port select --list postgresql
Password:
Available versions for postgresql:
 none
 postgresql91 (active)
 postgresql92

calvin$ sudo port select --set postgresql postgresql92
Selecting 'postgresql92' for 'postgresql' succeeded. 'postgresql92' is now active.

calvin$ sudo port select --list postgresql
Available versions for postgresql:
 none
 postgresql91
 postgresql92 (active)

Now, running `pip install psycopg2` in our python virtual environment will correctly build our psycopg2 against our postgresql 9.2 server.

calvin$ pip install psycopg2
Downloading/unpacking psycopg2
 Downloading psycopg2-2.4.5.tar.gz (719kB): 719kB downloaded
 Running setup.py egg_info for package psycopg2

 no previously-included directories found matching 'doc/src/_build'
Installing collected packages: psycopg2
 Running setup.py install for psycopg2
 building 'psycopg2._psycopg' extension
 /usr/bin/clang -fno-strict-aliasing -fno-common -dynamic -pipe -O2 -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090202 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/opt/local/include/postgresql92 -I/opt/local/include/postgresql92/server -c psycopg/psycopgmodule.c -o build/temp.macosx-10.7-x86_64-2.7/psycopg/psycopgmodule.o
 /usr/bin/clang -fno-strict-aliasing -fno-common -dynamic -pipe -O2 -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090202 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/opt/local/include/postgresql92 -I/opt/local/include/postgresql92/server -c psycopg/green.c -o build/temp.macosx-10.7-x86_64-2.7/psycopg/green.o
 /usr/bin/clang -fno-strict-aliasing -fno-common -dynamic -pipe -O2 -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090202 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/opt/local/include/postgresql92 -I/opt/local/include/postgresql92/server -c psycopg/pqpath.c -o build/temp.macosx-10.7-x86_64-2.7/psycopg/pqpath.o
 /usr/bin/clang -fno-strict-aliasing -fno-common -dynamic -pipe -O2 -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090202 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/opt/local/include/postgresql92 -I/opt/local/include/postgresql92/server -c psycopg/utils.c -o build/temp.macosx-10.7-x86_64-2.7/psycopg/utils.o
 /usr/bin/clang -fno-strict-aliasing -fno-common -dynamic -pipe -O2 -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.4.5 (dt dec pq3 ext)" -DPG_VERSION_HEX=0x090202 -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -I. -I/opt/local/include/postgresql92 -I/opt/local/include/postgresql92/server -c psycopg/bytes_format.c -o build/temp.macosx-10.7-x86_64-2.7/psycopg/bytes_format.o

Q.E.D.

Next! :-)

One of the trickier problems when managing multiple projects involve supporting different versions of open source library or software that your varying projects depend on.

In my current scenario, I need to support web projects which are still running on postgresql 9.1, while building up new projects which uses postgresql 9.2.

Getting postgresql92, postgresql92-server packages installed via macports is the easy part.

$ sudo port install postgresql92 postgresql92-server

A simple `port install` command does the  job.  The problem is getting making sure that they run alongside each other so that I can switch out from working on a project that uses postgresql 9.1 server easily to another project that uses postgresql 9.2.

Once our macports install completes running, we will create our initial database. Like so:

$ sudo mkdir -p /opt/local/var/db/postgresql92/defaultdb
$ sudo chown postgres:postgres /opt/local/var/db/postgresql92/defaultdb
$ sudo su postgres -c '/opt/local/lib/postgresql92/bin/initdb -D /opt/local/var/db/postgresql92/defaultdb'

Nothing surprising here. Except that our postgresql 9.1 server has occupied the default 5432, so we will need to make sure that our postgresql 9.2 server uses a different port.  Opening up our postgresql 9.2 server’s postgresql.conf file with `sudo vim /opt/local/var/db/postgresql92/defaultdb/postgresql.conf`,we set our postgresql 9.2′s port to a different one.

port = 5433 # (change requires restart)

Once our postgresql 9.2 server is properly initialized, we can manually start it using

$ sudo su postgres -c '/opt/local/lib/postgresql92/bin/postgres -D /opt/local/var/db/postgresql92/defaultdb'

which may not release the process to the background.

To release the process to the background, we can instead use Mac OSX’s daemondo. Like this:

$ sudo daemondo --label=postgresql92-server --start-cmd /opt/local/etc/LaunchDaemons/org.macports.postgresql92-server/postgresql92-server.wrapper start

Finally, to ensure that our postgresql 9.2 server starts up everytime we boot up our Mac, alongside our postgresql 9.1 server, we can set

$ sudo launchctl load -w /Library/LaunchDaemons/org.macports.postgresql92-server.plist

No different from our we make `launchctl` start up postgresql 9.1 server when our Mac boots up.

To check that our postgresql 9.2 server is indeed running, we can execute:

$ psql92 -p 5433 -U postgres
psql92 (9.2.1)
Type "help" for help.
postgres=#

From now on, we will have to be sure that settings and configuration for projects that try to connect to our postgresql 9.2 server uses port 5433.

One more thing – Postgis 2.0.

$ sudo port -v install postgis2 +postgresql92 +raster +topology

Since we use postgis regularly in our projects (for applications requiring GIS functionalities), we need to install the version compatible with postgresql 9.2. This is trivial with Postgis 2.0(.1). We no longer need to go through multiple steps to create a template spatial database (“template_postgis”). In Postgis 1.5, we need to initialize our database with this “template_postgis” template spatial database that we create.

From Postgis 2.0 onwards, it’s straightforward.

$ psql92 -p 5433 -U postgres -d your_db

psql92 (9.2.1)
Type "help" for help.

your_db=#  CREATE EXTENSION postgis;

your_db=# CREATE EXTENSION postgis_topology;

The 2nd `CREATE EXTENSION postgis_topology` is optional at this time of writing as geodjango does not have the necessary functionality to support Postgis’ Topological features yet.