PostgreSQL Interview Questions and Answers

Last updated on Feb 08, 2024
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PostgreSQL Interview Questions

We are going to discuss the most interviewer asked PostgreSQL interview questions for the acknowledgment of future aspirants in this niche. PostgreSQL is one of the most advanced, object-relational database management systems and open-source developed by PostgreSQL Global Development Group at Berkeley Computer Science Department, University of California. With its strong hand on proven data integrity, reliability, architecture, extensibility, and excellent feature set, PostgreSQL has earned the prominence of being a superior and robust solution globally, thus highly increasing the employment base for this niche.

With the operation freedom of all major operating systems including UNIX, Windows, Linux, and Mac OS X; PostgreSQL supports images, text, video as well as sound, and includes programming interfaces for C, C++, Perl, Java, Tcl, Ruby, and Open Database Connectivity.

Quick Questions about PostgreSQL
What is the Latest Version of PostgreSQL? 13.1 released on 12 November 2020
When was PostgreSQL Initial released? 8th July 1996
What language does PostgreSQL use? C Language
Who developed PostgreSQL? Michael Stonebraker
What operating system use PostgreSQL? Windows, Linux, macOS, OpenBSD

Now, let’s discuss an advanced set of PostgreSQL interview questions further above for candidates searching for a near-future job change or going to start their career from the ground level.

Most Frequently Asked PostgreSQL Interview Questions

Here in this article, we will be listing frequently asked PostgreSQL Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

Q1. What is PostgreSQL and why it is used for?

It’s a general purposed and advance object-relational database management system used to add custom functions developed using a various programming language such as C, C++, Java, etc. Designed to be extensible, PostgreSQL implements MVCC or multi-version concurrency control.

Q2. How to select first 10 records in PostgreSQL?

To get the first 10 records from a database in PostgreSQL, use the LIMIT command.

Here is an example of picking the first 10 records from a database called Example:


select * from users order by name desc LIMIT 0, 10

Q3. What is base directory in PostgreSQL?

The base directory in PostgreSQL (data_dir/base) is the folder is where PostgreSQL stores all the data you have inserted in your databases. It contains all the sub-directories which are used by a database in your clusters.

Q4. How to change the datatype of a column in PostgreSQL?

To change the records type of a column, you use the ALTER TABLE assertion as follows:


ALTER COLUMN username[SET DATA] TYPE new_data_type;

Q5. What is the Maximum size for a table in PostgreSQL?

Even though PostgreSQL has unlimited database size for users, but it has a limit for maximum table size. The maximum table size is set to 32 TB.

Note: This is very essential PostgreSQL interview questions.

Q6. What are the features of PostgreSQL?

PostgreSQL has many exciting features added to it. Here are a few of them:

  • By protecting data integrity, users can build a fault-tolerant environment.
  • Easy compatibility with significant platforms, languages, and middleware.
  • Multi-version concurrency control is supported.
  • The client-server network architecture is supported.
  • Trigger-based and log-based replication SSL
  • High availability and standby server
Q7. What is pgAdmin and how do you set up pgAdmin?

PgAdmin is a free, open-source PostgreSQL database administration GUI that is used in Microsoft Windows, Mac OS X, and Linux systems. PgAdmin is used for database server information retrieval, development process, Quality testing, and other ongoing maintenance.

Follow these steps to install PgAdmin:
  • Launch pgAdmin 4.
  • Go to the “Dashboard” tab, click on the “Quick Link” section and then click on “Add new Server”
  • Now, select the “Connection” tab in the “Create-Server” window.
  • Now, configure the connection as follows:
  • Enter your server's IP address in the “Hostname/Address” field.
  • Specify the “Port” as “5432”.
Q8. What does GEQO stands for in PostgreSQL?

In PostgreSQL, GEQO stands for Genetic Query Optimization. It allows the PostgreSQL search query optimizer to support large joined queries in an effective manner using a non-exhaustive search technique.

Q9. What is the Maximum size for a database in PostgreSQL?

PostgreSQL has no maximum database size, so users can put unlimited data into it. But, the table, row, and field size are limited. The row and indexes are also universal for its users.

PostgreSQL usually stores its desk facts in chunks of 8KB. The quantity of these blocks is confined to a 32-bit signed integer, giving the most desk dimension of 16TB.

Q10. Which is better MySQL or PostgreSQL?

In terms of learning databases, MySQL is perfect. It is the first choice for web-based projects merely requiring a database for transactions and nothing else. But, PostgreSQL is better in terms of functionalities and performance. It is more used in the execution of complex queries, data warehousing, and data analysis.

Benefits of PostgreSQL

  • Enterprise-class functions and performance with an open-source database management system with unlimited development possibilities.
  • Superior development possibility with diverse community purposed modules.
  • Store Procedure functions can be used for a server environment.
  • It offers diverse indexing techniques.
  • Availability of full-text search
  • Diverse extension functions and replications
Reviewed and verified by Baliram Prasad
Baliram Prasad

Baliram Prasad is a Technical Lead in Coldfusion. I am working closely with B2C and B2B Clients. I am having 13+ years of experience. I love programming and most of my time goes in learning the best w...