Steps to install PostgreSQL on Redhat Linux

Repository method

download link : postgresql.org/downloads

https://yum.postgresql.org/repopackages/

pgdg-redhat-repo-latest.noarch.rpm

This does not install PostgreSQL.
This is used to generate a repository which will list out all the PostgreSQL versions available.
That is the only job of this.
So this once again does not generate PostgreSQL or install PostgreSQL

 

As a root user

#dnf -qy module disable postgresql

The above will disable the inbuilt PostgreSQL which comes along with RHEL 8 and CentOS 8 versions

To list all PostgreSQL modules which are available for download
=======================================================

# yum list module postgresql*

To list all PostgreSQL 12 modules which are available for download
=======================================================

# yum list module postgresql12*

How do we install

#yum install postgresql12-server.x86_64 postgresql12-contrib.x86_64

postgresql12-contrib.x86_64 —> to install additional packages

Setup postgresql environment variables on Linux
======================================================

To verify the “postgres “superuser has been created

# su – postgres
$

means superuser is existing.

==> when we install postgresql , there is no option to give password for postgres user
reset the password
======================
# passwd postgres
enter NEW password
confirm password:

to check installer started the postgres
=====================================
systemctl status postgresql-12

o/p no cluster has been initialized hence postgreSQL service not started.

reasons
No cluster
Installation binaries does not know about data firectory

in windows postgresql instance was ready after installing the software because during the installation :
Cluster was initialized
System was started
service was running

In Linux the above tasks will be done manually

Setting up environment variable
===============================

su – postgres

vi .bash_profile

we can see the PGDATA variable is already set

PGDATA=/var/lib/plsql/12/data
export PGDATA

PATH=/usr/pgsql-12/bin:$PATH

Note : We can also create a user with our choice and install the postgresql software , then we need to set the .bash_profile under that user.