45 PostgreSQL DBA Interview Questions (With Sample Answers)

By Indeed Editorial Team

Published 29 September 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

PostgreSQL is an open-source object-relational database management system that is useful for adding custom functions developed using various programming languages. When preparing for a role in PostgreSQL, you can expect questions on topics like database servers and the difference between PostgreSQL and other database management systems. Anticipating and preparing questions regarding this database can help you prepare answers for a database administrator or DBA role. In this article, we explore frequently asked PostgreSQL DBA interview questions and provide you with some example answers to take inspiration from and answer questions confidently.

General PostgreSQL DBA Interview Questions

The interviewer may ask a few, general PostgreSQL DBA interview questions to know more about your personality, character traits, work ethic and career goals. This helps them better understand if you are an ideal candidate for the job. Here are some general interview questions you can review for your upcoming interview:

  1. What are your biggest strengths and weaknesses?

  2. Why do you want to work with this company?

  3. What do you feel is your significant professional achievement?

  4. How would your most recent manager or team leader describe you?

  5. What is your comfort level when working in an agile work environment?

  6. What are your aspirations as a PostgreSQLDBA?

  7. What were your previous employer's goals and how did you contribute to them?

  8. What are your salary expectations?

  9. How do you work under pressure?

  10. How do you like to spend your time outside of the workplace?

  11. What can we expect from you as a PostgreSQLDBA in the first three months of joining the organisation?

  12. How do you simplify complex ideas when speaking to a group of people with different levels of technical knowledge and capabilities?

  13. Do you have any questions for us?

  14. Why are you leaving your current organisation?

Related: Interview Question: 'What Are Your Strengths And Weaknesses?'

Questions About Experience And Background

Here are some PostgreSQL DBA interview questions an interviewer might ask you about your experience and background:

  1. How many years of experience do you have working as a PostgreSQL DBA?

  2. What versions of the PostgreSQL database are you most familiar?

  3. Name the different data types used in PostgreSQL.

  4. Explain multi-version control.

  5. What are tokens?

  6. Outline the difference between role and user.

  7. What is a checkpoint and when does a checkpoint happen in PostgreSQL?

  8. How do you start and stop the database server?

  9. How do you check whether the PostgreSQL server is up and running?

  10. Name the languages supported by PostgreSQL.

  11. What are the functions of PostgreSQL?

  12. What are indices and triggers in PostgreSQL?

Related: 7 Experience Interview Questions (With Sample Answers)

In-Depth Questions

An interviewer may ask these questions to test your knowledge of the subject and problem-solving skills. Here are some in-depth questions you may encounter during your interview:

  1. What process do you follow when users complain about database performance?

  2. Have you ever committed a mistake while using the PostgreSQL database? How did you overcome the challenging situation?

  3. How to find the database size?

  4. Explain the step to create a new database in PostgreSQL.

  5. How can you stop a particular database in the PostgreSQL cluster?

  6. Write the command for selecting the first 11 records.

  7. How can you change the data type of a column?

  8. Differentiate between MongoDB and PostgreSQL.

  9. What is a child in PostgreSQL?

  10. How do you prevent unnecessary unlocking of a database?

  11. What are database callback functions called and what are their purposes?

  12. Write the steps required to delete complete data from an existing table.

  13. How do you store the binary data in PostgreSQL?

  14. What is the purpose of table space in PostgreSQL?

Related: 6 Technical Phone Interview Questions With Sample Answers

5 Interview Questions With Sample Answers

During your interview, answers questions using the STAR interview technique. In the STAR technique, you describe a specific problem, explain your role or task, describe the action you took to solve the problem and explain how your efforts led to a resolution. Here are five interview questions with example answers to help you create effective responsiveness:

1. Describe your experience with PostgreSQL.

This question help shows your familiarity with PostgreSQL. Briefly describe your experience and expertise using this database management system. When answering, give details about the previous project you completed using this database.

Example: ‘I have been using PostgreSQL for three years in most of the applications I write. Due to its ease of use and powerful geospatial functions, it is the default choice for a relational database. PostgreSQL uses multi-version concurrency control (MVCC) to ensure the data I provide is consistent. It also supports JSON and regex, which helps me solve and handle parallel queries. In one of my previous projects, I was working with a financial institution and using the online transaction processing (OLTP) capabilities I created a secure and high-performing application compliant with regulatory standards.'

Related: What Is A Relationship In Database? (Definition And Types)

2. What are the advantages of using PostgreSQL?

Interviewers might ask this question to understand how you process database challenges. This question might help you to show a deeper knowledge of using PostgreSQL. In your answer, clearly outline why the database is helpful.

Example: ‘As it is an open-source database management system, I can easily access the source code of PostgreSQL, implement it and change it according to the project's requirements. It is an easy-to-learn system and I spent a few days mastering and learning the database management system. Another reason I prefer using PostgreSQL is that it is a high-risk tolerant database widely used in large web applications. Even my colleagues prefer this database management system because it requires low and easy maintenance for enterprise and embedded usage.'

Related: Relational Database Management Systems: MySQL Vs MSSQL

3. What are some disadvantages of using PostgreSQL?

Questions on disadvantages help an interviewer determine that you know the challenges associated with using PostgreSQL. When answering, explain the disadvantages of using this relational database. It shows your problem-solving capabilities and conveys that you can be calm and confident when working under stress.

Example: ‘While using PostgreSQL in my previous project, I found it difficult to create replications, reducing its popularity. Another issue I frequently encountered while working on large web applications is that the database is slower than MySQL. Interestingly, MySQL can outperform the speed and performance of PostgreSQL in many instances. As PostgreSQL focuses on compatibility, the changes I make to improve the speed require more work.'

Related: MySQL Interview Questions And Sample Answers

4. Outline the difference between PostgreSQL and MySQL.

Whenever an employer asks you about the difference between these two terms, you get the opportunity to elaborate on two concepts. An employer might ask this question to test whether you know when and where to which database. When answering this question, try to show your knowledge of both.

Example: ‘MySQL is a user-friendly database ideal for web-based projects because it requires only a database for transactions. PostgreSQL is a database that provides superior performance and functionality. Typically, I use PostgreSQL to execute complex queries, data analysis and data warehousing. While PostgreSQL is freely licensed and provides a powerful community, MySQL is GPL licensed and belongs to Oracle. I consider PostgreSQL when an application might grow to enterprise scope and require frequent write operations. If the application is not likely to scale up in coming years, using MySQL makes more sense.'

Related: Difference Between MySQL And SQL (With Definitions)

5. Name the phenomenon that you can prevent between concurrent transactions in PostgreSQL.

This question might help you show that you have a firm knowledge of using PostgreSQL. It shows your expertise because only an experienced professional can correctly name the three phenomena. When answering, name each phenomenon and briefly explain them.

Example: ‘The three unwanted phenomena in PostgreSQL are non-repeatable, dirty and phantom read. Non-repeatable read is a transaction that re-reads the data already read and searches for another transaction with already modified data. A dirty read is a transaction that reads data written by concurrent uncommitted transactions. In comparison, phantom read helps re-execute a query and returns a set of rows that satisfies the search condition. The query searches for the location of rows that satisfy the condition, which might have changed because of another committed transaction.'

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