Everything you need to know to prepare for a PostgreSQL Interview

While becoming a Developer has become one of the most prosperous career choices today, employers are constantly looking for professionals with advanced and specific skills. Knowledge of PostgreSQL, understanding its principles, use and potential is one of the most sought-after and sometimes even mandatory requirements on the modern IT job market.

Therefore, being prepared for PostgreSQL interview questions will certainly become your key advantage when you apply for the desired Developer’s position.

It is essential to understand the preparation for the interview does not only imply knowledge of the subject. A PostgreSQL is not an exam, but mostly a way for the prosperous employer to understand whether you are suitable for the job in general, can be efficient, focused and withstand the pressure.

Therefore, most probably, you won’t be given more than a minute to answer each question and make the right impression. In other words, being prepared for the PostgreSQL interview should combine knowledge of the subject with the ability to demonstrate your competence eloquently.

Let’s go over the fundamental meaning of PostgreSQL and its features that made this database so popular today so it would be easier to understand why PostgreSQL interview questions arise more and more often.

And of course, we shall overview the most essential and frequently asked PostgreSQL interview questions today.

Things you should know about PostgreSQL.

There is a reason why PostgreSQL has become one of the top databases today. Being an open-sourced Data Base Management System (DBMS), it is created with an SQL language in mind and supports JSON data-interchange format.

In other words, PostgreSQL is mostly appreciated for its ability to comply with fundamental operating systems such as Linux, UNIX, and Windows and its versatility. Frequent updates is another factor that allows PostgreSQL to always remain relevant, versatile and therefore – popular.

Above all, this PostgreSQL has certain distinguishing factors that distinguish it favourably from other popular DBMS’s:

• It lets a Developer built unique data types – this feature is most useful for companies that deal with any database outside of the standard built-in PostgreSQL package or even any other known DBMS;
• It allows a developer to create a multi-model software architecture;
• PostgreSQL’s XML features allow for direct XML data querying – XML data is becoming the fundamental feature for various companies;
• PostgreSQL offers 12 authentication systems, which allow a seamless connection between the database server and the database client;
• It is supported by over 80 Integrated Development Environments (IDEs) – it provides the highest chances that your framework will be perfectly compilable with this DBMS.

All those features make PostgreSQL and professionals who are trained for it the most sought-after on the modern market. This level of expertise can guarantee the most advanced career and financial perspectives. No wonder PostgreSQL Interview questions are among the most frequent ones for Developer positions today.

Being one of the most experienced educators in the field, CRS Info Solutions constantly monitors the trends in job interviews to provide aspirants with the most relevant information and prepare them thoroughly for the seamless start of their career path.

Let’s go over the most commonly-asked PostgreSQL Interview questions and answers that will demonstrate your knowledge as well as your ability to apply and demonstrate it efficiently.

What is PostgreSQL?

PostgreSQL (or Postgres) is an Object-Relational Database Management System used mainly in large web applications. It extends and uses the SQL language complemented with safety and storage features that are capable of the most intricate work frames.

Which major data types does PostgreSQL support?

PostgreSQL supports the following datatypes:

• UUID;
• Arbitrary precision numeric;
• Geometric primitives;
• Numeric types;
• Boolean;
• XML;
• Character types;
• Temporal types;
• Arrays.

Define multi-version control in PostgreSQL

Multi-Version Concurrency Control (MVCC) is a feature used in PostgreSQL to avoid unwanted database locking. It keeps all the transactions with the database as a record and removes the time lag feature unless some third-party is trying to access the database content.

What are the Tokens in PostgreSQL?

Tokens in PostgreSQL are technically the building blocks of the source code. Tokens can appear as:

• Constants; 
• Quoted identifiers;
• Other identifiers; 
• Keywords.

They can be used to create predefined commands and meaning or represent variables like tables, columns, etc.

Define pgadmin in PostgreSQL.

pgadmin is a feature responsible for the creation of a graphical front-end administration tool. It is a fundamental feature available under free Artistic License software released.

What is the meaning and purpose of pgadmin in PostgreSQL?

It is an administration tool for Windows, Mac OS X, and Linux systems. The functions of pgadmin are:

• Information retrieval;
• Development;
• Testing;
• Ongoing maintenance of Databases

How to update statistics in PostgreSQL?

To update statistics in PostgreSQL, one should use the function called Explicit “Vacuum” Call. This method technically creates a vacuum in the analysis option, which allows to easily update the statistics in PostgreSQL.

The syntax for the function is VACUUM ANALYZE.

Explain the command enable-debug in PostgreSQL.

This command is used for the compilation of all the libraries and applications. Although the procedure tends to hamper the overall system, it also boosts up the binary file size. However, debugging is essential for Developers as it helps them to recognize and eliminate a coding issue that affects the script.

What is CTID in PostgreSQL?

CTID is a field of every PostgreSQL table. The purpose of CTID is to identify specific physical rows according to their block and offset positions within a particular table.

A logical row’s CTID changes when it is updated, so the CTID cannot be used as a long-term row identifier. However, once no competing update is expected in the given PostgreSQL table, it can be used for row identification.

Define Cluster Index and Non-Cluster Index. What is the difference between them?

• Cluster index – used to sort table data rows on the basis of their key values. In RDBMS, the primary key allows us to create a clustered index based on that specific column.
• Non-clustered index – an index where the order of the rows does not match the physical order of the actual data. It is instead ordered by the columns that make up the index.

Final thoughts

Although we have provided the 10 most frequently asked PostgreSQL Interview questions in the form of a conversation, you should be prepared for the possibility that the interviewer will move from one topic to another, trying to learn as much as possible about your qualification in a strictly limited timeframe.

That is, it is essential to give short answers that would get straight to the point rather than lead the conversation away. Remember that the interview is rather a test of your efficiency and ability to use the knowledge rather than an exam on what you have learned at your previous training.

The focus on the mindset, along with enough hands-on experience and necessary certification, is the key success features that open determined aspirants the path towards their professional ambitions.