PostgreSQL Database on Ubuntu 20

postgresql-ubuntu.md

PostgreSQL on Ubuntu

⚠️ I would rather recommand to install PostgreSQL inside docker.

Add PPA Source

sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
sudo apt-get update

# Install the latest version
sudo apt-get -y install postgresql

Start/stop postgresql service

sudo service postgresql start
sudo service postgresql stop
sudo service postgresql restart

Access psql prompt

• Notice: we are accessing psql using a special user

sudo -u postgres psql

• Type \q and enter to exit prompt.
• Remember: psql is equivalent to mysql

Create a new postgres user

• By default postgres comes with a special user named postgres but we will not be using this for our web apps.
• This user is to perform administration only. So lets create a new user with the help of this super user.
• Notice that postgres is a linux user.

sudo -u postgres createuser --interactive --pwprompt

Answer the questions asked.

Create a new database

sudo -u postgres createdb --owner=user_name db_name_goes_here

If you dont have the user_name as a linux user in your machine then you need to add, otherwise you will get unable to initialize policy plugin error on terminal. This is called Ident authentication in postgres.

# create missing linux user
sudo adduser user_name

You can omit --owner=user_name parameter if db_name is same as user_name.

Login to psql propmt via super user

• Lets you perform adminstrative commands on this database.
• You would rarely login with postgres user.

sudo -u postgres psql -d db_name_goes_here

Login to psql prompt via this user

sudo -u user_name psql db_name_goes_here

Connect to database

Host: 127.0.0.1
Post: 5432
User: user_name_you_created_above
Password: this_should_be_the_postgres_user_password
Database: db_name_you_just_created

Delete database

sudo -u postgres dropdb db_name

Delete user

sudo -u postgres dropuser user_name

Import/export database

# export
pg_dump -U user_name db_name > dbexport.pgsql
# import 
pg_dump -U user_name db_name < dbexport.pgsql

Run SQL query from terminal

sudo su linux_user_name_that_owns_the_database
psql -U user_name -d database_name -W

Now you can run your queries like:

select * from users;

Install PostGIS extension

#sudo add-apt-repository ppa:ubuntugis/ubuntugis-unstable
#sudo apt update
sudo apt install postgis

Now enable the extension on this database

sudo -u postgres psql -d db_name_goes_here
CREATE EXTENSION IF NOT EXISTS postgis WITH SCHEMA public;
\q

Eject extension from specific database

DROP EXTENSION postgis;

Resources

• https://www.linode.com/docs/databases/postgresql/how-to-install-postgresql-on-ubuntu-16-04/
• https://www.digitalocean.com/community/tutorials/how-to-install-and-use-postgresql-on-ubuntu-16-04
• https://www.digitalocean.com/community/tutorials/how-to-secure-postgresql-on-an-ubuntu-vps
• https://dev.to/jkostolansky/how-to-upgrade-postgresql-from-11-to-12-2la6

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