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Table of contents
1.
Introduction
2.
Basic PostgreSQL Interview Questions and Answers for Freshers
2.1.
1. Describe Postgresql.
2.2.
2. What are the features and capabilities of Postgres DB?
2.3.
3. What does PostgreSQL's Multi-Version Concurrency Control mean?
2.4.
4. What is a ctid in PostgreSQL?
2.5.
5. Provide a brief explanation of the functions in PostgreSQL?
2.6.
6. Which is superior, PostgreSQL or MySQL?
2.7.
7. Describe pgadmin?
2.8.
8. What does "Multi-version Control" mean?
2.9.
9. What does PostgreSQL table partitioning entail?
3.
Intermediate PostgreSQL Interview Questions and Answers
3.1.
10. What do PostgreSQL indexes do?
3.2.
11. What do PostgreSQL tokens mean?
3.3.
12. How are queries involving several databases carried out?
3.4.
13. Describe PostgreSQL Functions in detail.
3.5.
14. Explain Triggers.
3.6.
15. What kinds of Data Types does Postgresql support?
3.7.
16. Is it possible to set up a PostgreSQL server cluster with shared storage?
3.8.
17. What exactly are string constants?
3.9.
18. What Different Postgresql Enhancements Are Made To The Straight Relational Data Model?
4.
Advanced PostgreSQL Interview Questions and Answers for Experienced
4.1.
19. How are Postgresql stats updated?
4.2.
20. What contrasts exist between Postgresql and NoSQL?
4.3.
21. What Has Changed in Postgre 9.1?
4.4.
22. Is Postgresql a Cloud-based Database?
4.5.
23. How Do Oracle/db2/ms SQL Server/Informix and Postgresql Compare?
4.6.
24. What are Connector Libraries?
4.7.
25. What is Full-Text Search? Does Postgresql offer support for it?
4.8.
26. What do you understand by inverted files in PostgreSQL?
4.9.
27. What drawbacks does PostgreSQL have?
4.10.
28. What is a Foreign Data Wrapper (FDW) in PostgreSQL, and how can it be used for data integration?
4.11.
29. What are Materialized Views in PostgreSQL, and how do they differ from regular views?
4.12.
30. What are Advisory Locks in PostgreSQL, and how can they be used for application-level locking?
5.
Frequently Asked Questions
5.1.
What is the main purpose of PostgreSQL?
5.2.
What is the latest version of PostgreSQL?
5.3.
Why is PostgreSQL the most loved database?
6.
Conclusion
Last Updated: Jun 14, 2024
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Top 30 PostgreSQL Interview Questions and Answers (2024)

Author Mayank Goyal
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18 Jun, 2024 @ 01:30 PM

Introduction

Object-relational database management system (ORDBMS) PostgreSQL, also referred to as Postgres, is one such technology. Initially created by the PostgreSQL Global Development Group in 1996, the stable release was made in 2018. Specifically, extensibility and standards compliance are emphasized. It manages large workloads, including those running simultaneously on macOS, Linux, and Windows, ranging from simple single-machine apps to massive Internet-facing applications with many concurrent users. To get chosen for the interview, review the wisdom jobs database of PostgreSQL interview questions and answers. Mumbai, Delhi, Bangalore, Pune, and Hyderabad are just a few cities where one can examine employment availability. Furthermore, we will be covering PostgreSQL Interview Questions that are frequently asked.

postgresql interview questions

Here, we've included a list of a few crucial and probable interview questions. The questions can be understood with practice, diligence, and hard work. If you read through the questions, you can discover several that are asked practically universally in interviews.

Basic PostgreSQL Interview Questions and Answers for Freshers

1. Describe Postgresql.

One of the most popular open-source databases in the world is this one. Additionally, this is utilized to make sophisticated applications. The object-relational database management system is used for this. Being familiar with Linux and UNIX can be helpful while using PostgreSQL.

2. What are the features and capabilities of Postgres DB?

The following are the main PostgreSQL features and functionalities:

  • Object-relational database.
  •  Flexibility and SQL support.
  • Flexible Application Program Interface and DB validation.
  • Procedural languages and Multi-Version Concurrency Control.
  • Client servers and WAL.

3. What does PostgreSQL's Multi-Version Concurrency Control mean?

An advanced technique used in PostgreSQL for enhancing database performance in a multi-user environment is called Multi-Version Concurrency Control (MVCC). PostgreSQL uses a multi-version environment, unlike lock models in other databases, so locks gained for reading data don't conflict with locks acquired for writing the data. Consequently, the procedure will be much quicker and more segmented.

4. What is a ctid in PostgreSQL?

Every PostgreSQL table has a ctid field. It designates the tuple location and is distinct for every record in a table. Records may be deleted with it. Remember that we should only utilize ctid if we are completely out of options for other unique identifiers.

5. Provide a brief explanation of the functions in PostgreSQL?

Functions are crucial in the server's ability to execute the code. PL/pgSQL, a native language of PostgreSQL, and other scripting languages like Perl, Python, PHP, etc., are some of the languages used to create functions. The functions' efficiency can also be improved using the statistical language PL/R.

6. Which is superior, PostgreSQL or MySQL?

MySQL is the ideal database to learn on. It is the top option for web-based programs that only need a database for transactions. However, PostgreSQL is superior in terms of features and speed. It is more frequently used for data warehousing, analysis, and executing sophisticated queries.

7. Describe pgadmin?

A feature called Pgadmin is recognized as a graphical front-end administrative tool. Free software produced under an artistic license includes this feature. The brand-new database management tool available under creative license is pgadmin iii. 

8. What does "Multi-version Control" mean?

MVCC, also known as multi-version concurrency control, prevents needless database locking. By doing this, the user's database login time is no longer delayed. When another user gains access to the content, this function or time lag appears. Records of each transaction are maintained.

9. What does PostgreSQL table partitioning entail?

Table partitioning in PostgreSQL refers to dividing a huge table into smaller portions. Through table inheritance, PostgreSQL allows list and range partitioning. Users must create each division as a child table of the master table.

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Intermediate PostgreSQL Interview Questions and Answers

10. What do PostgreSQL indexes do?

The index is a popular method for improving database performance in PostgreSQL. Compared to not having an index, it enables the database server to locate and retrieve particular rows more quickly. Additionally, it increases the overall overhead of the database system. Therefore users must apply them carefully.

The database search engine uses indexes, and specialized lookup tables, to speed up data retrieval. An index is a pointer to a particular piece of data in a table.

11. What do PostgreSQL tokens mean?

A token can be a word, a phrase, a quote, a literal (or constant), or a unique representation of a person's personality. Whitespace (space, tab, newline) is typically used to separate tokens. However, it is not required if there is no ambiguity (which is usually only the case if a unique persona is adjoining to some other token type).

12. How are queries involving several databases carried out?

There is no alternative way to query a database besides one already existing. A cross-database query's behavior for PostgreSQL is unclear because it loads database-specific system catalogs.

However, cross-database queries using function calls are supported by contrib or dblink. However, clients can also establish concurrent connections to various databases and combine the outcomes.

13. Describe PostgreSQL Functions in detail.

Functions are crucial because they provide the server's ability to execute code. One of the languages, PL/pgSQL, the native language of PostgreSQL, is capable of programming functions for effective use. Many languages, such as PHP, Perl, Python, etc., support scripting languages. Another option is to utilize the statistical language PL/R. 

14. Explain Triggers.

You can start an event by using a SQL query. INSERT and UPDATE queries can be used to activate triggers. Tables may be equipped with these. Multiple triggers may be activated alphabetically. These triggers can call functions written in other languages. 

15. What kinds of Data Types does Postgresql support?

Various data types are supported, including:

  •  Arbitrary precision numbers
  •  rudimentary geometric shapes
  •  arrays
  • XML, etc.

Users can build and index their indexes.

16. Is it possible to set up a PostgreSQL server cluster with shared storage?

They offer several different clustering tools that employ multiple clustering algorithms because no single type of clustering may meet all requirements. There are accessible open-source forks and proprietary tools like Greenplum Database, Citus Data, and others, and the open-source projects PostgresXC and Postgres-XL.

Additionally, filesystem-based clustering technologies for failover from Red Hat, Microsoft, Veritas, and Oracle are compatible with PostgreSQL.

17. What exactly are string constants?

Single quotes separate the characters in a string constant. This feature is utilized when inserting a character or providing a character to database objects. PostgreSQL permits using single quotes; however, they must be enclosed by a backslash in the C manner. This function is crucial for data parsing. 

18. What Different Postgresql Enhancements Are Made To The Straight Relational Data Model?

Postgre SQL offers several improvements over the basic relational data model, including inheritance, functions, extensibility, and support for multiple-choice arrays. Because it is object-oriented and refers to tables as classes, the jargon is unique.

Advanced PostgreSQL Interview Questions and Answers for Experienced

19. How are Postgresql stats updated?

A call to explicitly "vacuum" is performed in PostgreSQL to update statistics. I hope you are aware of how to do this. If not, please inform us so we can assist you. Postgresql statistics are updated using a vacuum with the option Analyze. The syntax is VACUUM ANALYZE; 

20. What contrasts exist between Postgresql and NoSQL?

It is nonsensical to compare and make general statements about "NoSQL" Databases (Not Only SQL), which are a diverse variety of non-relational databases ranging from tiny embedded databases to enormous clustered (HA/Sarding) data processing platforms like Hadood & MongoDB. Choosing between relational and non-relational databases is not unusual because non-relational databases have been side by side with relational databases for 40 years.

The following factors should be considered by users when choosing a database

  • Features,
  • Functionalities,
  • Scalability
  • Reliability,
  • Implementing HA capabilities (Replication)
  • Community assistance is needed for their current application.

Additionally, using numerous databases for large projects is becoming the norm, and PostgreSQL is by no means an exception. 

21. What Has Changed in Postgre 9.1?

As always, we cannot predict what will be accepted and what won't because the project has rigorous quality requirements, and certain patches may not be accepted in time. Only what is in development, such as synchronous replication, JSON support, security labels, nearest-neighbor geographic searches, SQL/MED external data connections, column-level collations, and index-only access, can be revealed. However, by the time 9.1 is launched, this feature list will have significantly changed. 

22. Is Postgresql a Cloud-based Database?

Yes. PostgreSQL is portable and runs well in virtual containers like other open-source databases. Heroku, GoGrid, and Joyent are just a few businesses that offer PostgreSQL in cloud hosting settings. 

23. How Do Oracle/db2/ms SQL Server/Informix and Postgresql Compare?

Most experts believe our feature set is quite competitive with other top SQL RDBMSes. There are qualities that some of them undoubtedly possess that we do not, and the opposite is also true. Few benchmarks have been released, revealing that PostgreSQL is only 10–30% slower than proprietary competitors. However, the performance of their PostgreSQL systems has left many of our users who migrated from other database systems—primarily Oracle and Informix—completely delighted. 

24. What are Connector Libraries?

It consists of several connectors that may be downloaded and altered in any ProcessMaker instance. The connector public library is managed and updated constantly by the ProcessMaker. 

25. What is Full-Text Search? Does Postgresql offer support for it?

It is a methodology or approach for searching a single or group of digitally recorded documents in a full-text database. It is simple to distinguish it from searches that use metadata or pieces of the original texts represented in databases.

PostgreSQL is not as sophisticated as Elasticsearch or SOLR, but both are designed specifically for full-text search tools. Full-text search is only a feature in PostgreSQL, though it is good. 

26. What do you understand by inverted files in PostgreSQL?

In PostgreSQL, an inverted file is an index data structure used to map content to its location in a database file, within a document, or in sets of documents. It generally includes the distinct words found in a text and a list containing the occurrences of a word in the text. It is used in a data structure for document retrieval systems to provide a full-text search. 

27. What drawbacks does PostgreSQL have?

There is more than one company that owns Postgres. As a result, although fully functional and similar to other DBMS systems, it has had problems building a brand.

  • Compared to MySQL, PostgreSQL requires more work to make changes for speed enhancement because it prioritizes compatibility.
  • Though many open source applications may not support PostgreSQL, MySQL is.
  • It is slower than MySQL in terms of performance measures.

28. What is a Foreign Data Wrapper (FDW) in PostgreSQL, and how can it be used for data integration?

FDW allows accessing external data sources (other databases or file systems) as if they were PostgreSQL tables. It enables seamless data integration and querying between PostgreSQL and other data sources.

29. What are Materialized Views in PostgreSQL, and how do they differ from regular views?

Materialized Views store the query results physically in the database, allowing faster access and reducing query processing time. Regular views are virtual and do not store data directly; they are based on the underlying tables and retrieve data on-the-fly when queried.

30. What are Advisory Locks in PostgreSQL, and how can they be used for application-level locking?

Advisory Locks are lightweight locks that can be acquired programmatically by applications for synchronization purposes. Unlike standard locks, Advisory Locks do not conflict with regular table-level locks and can be used for application-specific coordination.

Frequently Asked Questions

What is the main purpose of PostgreSQL?

The main purpose of PostgreSQL is to store, manage, and retrieve structured data for various applications, providing a reliable and powerful open-source database solution.

What is the latest version of PostgreSQL?

The latest version of PostgreSQL is 15. There are so many features they have introduced in this version. We will have a more secure permission model in this version. They have also added a MERGE operation in it and many other features.

Why is PostgreSQL the most loved database?

PostgreSQL is highly regarded and loved for its advanced features, extensibility, reliability, and adherence to SQL standards. This makes it more suitable for a wide range of applications. Additionally, its open-source nature fosters a strong community and continuous improvement.

Conclusion

In this article, we walked through all the important PostgreSQL interview questions, from basic to experienced. That's it from the article. I hope you all find it useful.

Apart from PostgreSQL interview questions, you can also refer to interview questions in domains like OOPS interview questionsSQL interview questionsAEM interview questions, and many more. Nevertheless, you may consider our paid courses to give your career an edge over others!

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