PostgreSQL installation and setup - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is PostgreSQL?

PostgreSQL is a free and open-source relational database system used to store and manage data efficiently.

beginner

Name the command to check if PostgreSQL is installed on your system.

You can check by running psql --version in the terminal or command prompt.

beginner

What is the default port number PostgreSQL listens on?

PostgreSQL listens on port 5432 by default.

beginner

After installing PostgreSQL, what is the first step to start using it?

You need to start the PostgreSQL server service and then connect using the psql command-line tool or a graphical client.

intermediate

What is the purpose of the pg_hba.conf file in PostgreSQL?

It controls client authentication, deciding who can connect to the database and how they must prove their identity.

Which command installs PostgreSQL on Ubuntu Linux?

A sudo apt install postgresql

B sudo yum install postgresql

C sudo pacman -S postgresql

D brew install postgresql

On Ubuntu, the package manager apt is used, so the correct command is sudo apt install postgresql.

What command starts the PostgreSQL service on a Linux system using systemd?

A service postgresql start

B systemctl start postgresql

C start postgresql

D pg_ctl start

The modern way to start services on Linux with systemd is systemctl start postgresql.

Which tool is used to interact with PostgreSQL from the command line?

A mysql

B pg_ctl

C pgadmin

D psql

psql is the command-line interface tool to interact with PostgreSQL databases.

What is the default username created during PostgreSQL installation?

A root

B admin

C postgres

D user

The default superuser account created is named postgres.

Where can you configure which IP addresses can connect to PostgreSQL?

A pg_hba.conf

B pg_ident.conf

C postgresql.conf

D pg_config

The pg_hba.conf file controls client authentication and allowed IP addresses.

Describe the basic steps to install and start PostgreSQL on a new Linux machine.

Think about commands and default settings.

Explain the role of configuration files in PostgreSQL setup, especially pg_hba.conf and postgresql.conf.

Focus on what each file controls.

Practice

1. Which of the following is the correct first step after installing PostgreSQL on your computer?

easy

A. Start the PostgreSQL service

B. Create a new database user

C. Write SQL queries immediately

D. Install a web browser

Solution

1. Step 1: Understand PostgreSQL service role

   PostgreSQL runs as a service that must be active to accept connections.

2. Step 2: Start the service after installation

   Before using PostgreSQL, you must start its service to enable database operations.

3. Final Answer:

   Start the PostgreSQL service -> Option A

4. Quick Check:

   Service must run before use = Start service [OK]

Hint: Always start the database service before using it [OK]

Common Mistakes:

• Trying to run queries before starting the service
• Assuming installation auto-starts PostgreSQL
• Skipping service start and expecting connection

2. Which command is used to start the PostgreSQL interactive terminal after installation?

easy

A. startpsql

B. psql

C. pgstart

D. postgresql

Solution

1. Step 1: Identify the PostgreSQL command-line tool

   The tool to interact with PostgreSQL databases is called psql.

2. Step 2: Confirm the correct command

   Typing psql opens the interactive terminal for running SQL commands.

3. Final Answer:

   psql -> Option B

4. Quick Check:

   Interactive terminal command = psql [OK]

Hint: Use 'psql' to open PostgreSQL terminal [OK]

Common Mistakes:

• Typing incorrect commands like 'startpsql' or 'pgstart'
• Confusing service start with terminal command
• Using 'postgresql' as a command

3. After installing PostgreSQL on Linux, which command correctly starts the PostgreSQL service?

medium

A. psql start

B. sudo start postgresql

C. service postgresql stop

D. sudo systemctl start postgresql

Solution

1. Step 1: Understand Linux service management

   Modern Linux uses systemctl to manage services like PostgreSQL.

2. Step 2: Use correct command to start service

   sudo systemctl start postgresql starts the PostgreSQL service properly.

3. Final Answer:

   sudo systemctl start postgresql -> Option D

4. Quick Check:

   Start service with systemctl = sudo systemctl start postgresql [OK]

Hint: Use systemctl to start services on Linux [OK]

Common Mistakes:

• Using 'service postgresql stop' which stops service
• Trying 'psql start' which is invalid
• Using 'sudo start postgresql' which is not a valid command

4. You installed PostgreSQL but get an error when running psql saying "could not connect to server". What is the most likely cause?

medium

A. PostgreSQL service is not started

B. You typed the wrong SQL command

C. Your computer is offline

D. psql command is deprecated

Solution

1. Step 1: Analyze the error message

   "Could not connect to server" means the client cannot reach the database server.

2. Step 2: Identify common cause

   The most common reason is the PostgreSQL service is not running, so no server is listening.

3. Final Answer:

   PostgreSQL service is not started -> Option A

4. Quick Check:

   Connection error = service not started [OK]

Hint: Check if PostgreSQL service is running when connection fails [OK]

Common Mistakes:

• Assuming SQL syntax error causes connection failure
• Thinking internet connection affects local server
• Believing psql is deprecated

5. You want to install PostgreSQL on Windows and start using it immediately. Which sequence of steps is correct?

hard

A. Install PostgreSQL -> Open psql terminal -> Start PostgreSQL service -> Download installer

B. Open psql terminal -> Download installer -> Install PostgreSQL -> Start service

C. Download installer -> Install PostgreSQL -> Start PostgreSQL service -> Open psql terminal

D. Start PostgreSQL service -> Download installer -> Install PostgreSQL -> Open psql

Solution

1. Step 1: Understand installation order

   You must first download and install PostgreSQL before starting its service.

2. Step 2: Start service before using psql

   After installation, start the PostgreSQL service to enable database access, then open psql.

3. Final Answer:

   Download installer -> Install PostgreSQL -> Start PostgreSQL service -> Open psql terminal -> Option C

4. Quick Check:

   Install -> Start service -> Use psql [OK]

Hint: Install first, then start service, then use psql [OK]

Common Mistakes:

• Trying to use psql before installation
• Starting service before installation
• Downloading installer after starting service