PostgreSQL is an Open Source Relational Database Module

Installation has thus far been somewhat difficult but I have had some success with the following on Manjaro Linux

# Installs postgresql and it's GUI pgadmin
sudo pacman -S yay
yay postgresql pgadmin4
sudo pacman -S postgres #allows for use of the initdb on Arch/Manjaro

# Setup the service
sudo -u postgres -i #login as postgres
initdb --locale $Lang -E -D '/var/lib/postgres/data/'

#This will then display on the console:
[postgres@manjaro ~]$ initdb --locale $LANG -E UTF8 -D '/var/lib/postgres/data/'
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

The database cluster will be initialized with locale "en_US.utf8".
The default text search configuration will be set to "english".

Data page checksums are disabled.

fixing permissions on existing directory /var/lib/postgres/data ... ok
creating subdirectories ... ok
selecting dynamic shared memory implementation ... posix
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting default time zone ... America/Los_Angeles
creating configuration files ... ok
running bootstrap script ... ok
performing post-bootstrap initialization ... ok
syncing data to disk ... ok

initdb: warning: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.

Success. You can now start the database server using:

    pg_ctl -D /var/lib/postgres/data/ -l logfile start

# Then we run:
sudo systemctl enable --now postgresql
# which will log the following:
Created symlink /etc/systemd/system/multi-user.target.wants/postgresql.service → /usr/lib/systemd/system/postgresql.service.
# and then...
sudo systemctl status postgresql #check for any errors

# To setup your connection security, login as root:
su

cd /var/lib/postgres/data
cp pg_hba.conf pg_hba.conf.backup # in case you mess up
micro pg_hba.conf

Although self explanatory, please also see:

https://dev.to/tusharsadhwani/how-to-setup-postgresql-on-manjaro-linux-arch-412l

For further details.  This is also the website from which this configuration was written.

Ok, so we got in using pgAdmin as well! (this actually took me a good minute and using the psql cli helped)

Firstly, its' good to initialize our database on port 5432, note the initdb command above.  Once done...

#login as postgres:
sudo -u postgres -i

#then login to postgres via cli gui:

 psql <dbname>


#then it may prompt you for the password, after logging in, you will be presented with a basic cli GUI:

postgres=# help
You are using psql, the command-line interface to PostgreSQL

#from here you can pretty much interact with the interface but if you want to run the same server on pgAdmin,
#open it up via the terminal or from your Manjaro GUI:

pgadmin4

from her eyou can go to object create server, where it will ask for your login input,
this was the hard part, but I eventually determined that via psql, you could find all the info by typing

postgres=# \conninfo

which displays:
You are connected to database "postgres" as user "postgres" via socket in "/run/postgresql" at port "5432".
the name can be put in whatever you like, since you're naming the server (i also used postgres for this...)
but at the connection under Host name/address took me a while to realize that what it wanted was /run/postgresql
and yes the default port is 5432.

So there we are, finally the installation is complete and running on Manjaro Linux!