How do I install older version of postgresql and postgis? - postgresql

Question

I am new to Linux and I found it really difficult to install older version of postgresql (along with postgis). I have uninstalled everything I could find connected to postgresql in aptidude. As only the newest version is available through apt-get install, I have went through several tutorials how to get 9.1 installed.
Example: https://wiki.postgresql.org/wiki/Apt (with 9.1 at the end, not 9.3)
After I was done with this tutorial, pgAdmin III is still showing 9.3 as version.
What's the correct way to dump 9.3 and install 9.1 as well as postgis 1.5?
I am using Mint 17

Answer 1

Okay. First off it is perfectly fine to run multiple versions of postgresql alongside one another. You can have more than one cluster on a box, and each cluster can run different versions. The debian pacakges are very well designed to make this easy to do.
However since you've indicated you're a newby to linux/postgresql it's probably best to get 9.3 completely cleaned from your system to avoid frustrating hiccups which will take you a long time to figure out.
To do this you need to:
Purge all postgresql 9.3 packages from dpkg
Manually delete any 9.3 data and configuration for 9.3 cluster
Make sure you've created a 9.1 cluster
Step 1 – purge DPKG
DPKG manages the packages on your system. APT acts as a mechanism for getting packages to install. A lot of DPKG functionality is available through apt, but some things are just easier on dpkg. In your comments you've shown that DPKG is still showing remnants of 9.3. When you uninstall a package some parts of it may hang around (such as configuration files). You can remove multiple packages in one command. To get rid of these completely you can tell dpkg to purge them dpkg --purge <package name>. You can remove multiple packages in one command and it's best to do so.
dpkg --list will list everything on your system. dpkg --list | grep postgresql searches this list for postgresql.
Step 2 – Manually delete data and configuration from the old 9.3 cluster.
When you first install postgresql it creates a cluster for you; no questions asked. This trips up a lot of new users because they neither knew that it happened nor how to replace it. Now that 9.3 is uninstalled you can go ahead and simply delete the configuration and data:
If there was anything you wanted to keep in the installed 9.3 database DO NOT run the following commands
sudo rm -rf /etc/postgresql/9.3 Removes the configuration.
sudo rm -rf /var/lib/postgresql/9.3 Removes the data.
Step 3 – Create a new cluster
You've indicated in comments that postgresql 9.1 is installed. Before you run this command it's worth reading the manual. man pg_createcluster.
sudo pg_createcluster 9.1 <think up a name>
Now you should be able to start up postgresql sudo service postgresql start
Edit
If pg_config is still listing the incorrect version then... this can be a result of remnants of 9.3 still left on your system. This may not be a problem. To allow multiple versions to run along side one another pg_config is a wrapper script which searches for the latest (highest version) of /usr/lib/postgresql/*/bin/pg_config. So what you're seeing is the result of running /usr/lib/postgresql/9.3/bin/pg_config. If 9.3 is completely cleaned from your system then /usr/lib/postgresql/9.3 should have gone.
If you want to see the configuration of 9.1 then try running:
/usr/lib/postgresql/9.1/bin/pg_config.
The wrapper scripts which starts the server will use the file structure of /etc/postgresql and use the apropriate version. So /etc/postgresql/9.1/main will startup version as 9.1.