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 Â job. Â 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. Â 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
Type "help" for help.
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
Type "help" for help.
your_db=# Â 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.