Postgres has the ability to create clusters of databases that run on the same machine concurrently. One thing that I did not know about postgres is that you can also run multiple versions of postgres at the same machine concurrently along with the mutliple clusters mentioned earlier. But how can one view information about all these instances and clusters and how can we connect to each of them and how can one upgrade the clusters running on one version to another?

I am running Debian on my personal computer and the rest of this post is going to be a very brief description of how I managed to upgrade and tidy up after my postgres instances running on my local computer. Please note that this is not an in depth post nor I suggest in any way this approach for a live / production upgrade of postgres.

So let’s get started!

First of all let’s see which versions of postgres are running on our box. As a super user execute the following command

PostgreSQL uses a pager to display the results of an operation you performed when you are using the command line tool (psql).

You can disable the pager by issuing:

pset pager off

with which you specifically request that the pager is disabled. You can re-enable the pager by issuing:

pset pager on

with which you specifically request that the pager is enabled. Alternatively you can toggle the status of the pager by issuing

pset pager

which depending on the current status of the pager will either enable or disable it.