PostgreSQL Interview Questions
An Overview of PostgreSQL
PostgreSQL is one of the most advanced, object-relational database management system 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 have earned the prominence of being a superior and robust solution globally, thus highly increasing the employment base for this niche. We are going to discuss the most interviewer asked PostgreSQL interview questions for the acknowledgment of future aspirants in 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.
Now, let’s discuss an advanced set of PostgreSQL interview questions and answers for experienced further below for candidates searching for a near future job change or going to start their career from the ground level.
- 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.
- Offers diverse indexing techniques.
- Availability of full-text search
- Diverse extension functions and replications
Related Interview Questions and Answers
- MySQL Interview Questions
- MongoDB Interview Questions
- SQLite Interview Questions
- Dbms Interview Questions
- Oracle Interview Questions
- Rdbms Interview Questions
- DB2 Interview Questions
Most Frequently Asked PostgreSQL Interview Questions And Answers With Examples:
- What is PostgreSQL and why it is used for?
- Please explain PostgreSQL features?
- Please explain the features of PostgreSQL?
- Please explain how to PostgreSQL install on windows?
- Please explain how to PostgreSQL install Ubuntu?
- How to uninstall PostgreSQL Ubuntu?
- Please explain the PostgreSQL data type?
- How to change the datatype in PostgreSQL?
- What is the latest version of PostgreSQL?
- What is the dual table in PostgreSQL?
- What is the PostgreSQL database size?
- What is a child in PostgreSQL?
- Please explain PostgreSQL vs. MySQL?
- What is table partitioning in PostgreSQL?
- What is the maximum size of the table in PostgreSQL?
- Please explain postgresql vs sql server?
- Please explain PostgreSQL vs. Oracle?
- How to stats update in PostgreSQL?
- Please explain PostgreSQL vs. MongoDB?
- What do you mean by indices of PostgreSQL?
- What is MVCC (multi-version concurrency control) in PostgreSQL?
- What do you mean by indexes of PostgreSQL?
- What types of indexes are supported in PostgreSQL?
- How to start PostgreSQL on Windows?
- How to stop PostgreSQL on Windows?
- What is the command to find a version of PostgreSQL?
- What is pgAdmin and how to install pgAdmin?
- What is write-ahead logging in PostgreSQL?
- Please explain PostgreSQL transaction log location?
- How to create a database in PostgreSQL pgAdmin?
- What are tokens in PostgreSQL?
- Please explain Postgres reserved words?
- How to Postgres change user password?
- What is a sequence in PostgreSQL?
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.
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
- And more...
- Download Windows PostgreSQL one-click the installer and run it.
- Choose to install PostgreSQL as a Windows Service.
- If needed, change the installation directory and click next
- Choose the components you want to install & click next
- If needed, change the data location
- Enter the user password and if necessary make a note of it.
- Let the port number by the default
- Once the installation is complete, uncheck the Stack Builder prompt and click finish
- Now go to start menu, search and start pgAdmin 4
- Click on servers present on the pgAdmin homepage and choose Postgre SQL 10
- Enter the superuser password, and the dashboard will begin for your use
As the default repositories of Ubuntu contain Postgres packages, we can install it easily using the apt packaging system. Refresh the local package index and then install the Postgres packages and a -contrib package which adds additional functionality and utilities. The PostgreSQL software installation process is finished now.
To uninstall, PostgreSQL in Ubuntu, follow these steps:
- At first, check Postgres related folders using
ubuntu@ip:~/anvesh$ dpkg -l | grep Postgres
- Now command the following to remove the remaining files
ubuntu@ip:~/anvesh$ sudo apt-get --purge remove PostgreSQL PostgreSQL-doc
- Again check Postgres related folders
- Remove all the pending folders using the following
ubuntu@ip:~/anvesh$ sudo apt-get --purge remove postgresql postgresql-client-9.6 postgresql-common pgdg-keyring
- Now PostgreSQL is uninstalled.
The PostgreSQL 11.2 is the latest version of this open database management system. Recently, PostgreSQL Global Development Group has released a periodic update to all its supported version including 9.4.21, 9.5.16, 9.6.12, 10.7 and 11.2.
In PostgreSQL, the DUAL table is a special one-column, one-row table present by default. It is created as a view to easing porting problems, which allows code to remain compatible with Oracle SQL without obstructing the Postgres parser.
The ctid field exists in every PostgreSQL table. It is unique for every record in a table and denotes the turple location. It can be used to delete records. The thing to remember, we should only use ctid if we have absolutely no other unique identifier to use.
|1.||PostgreSQL is open-source software.||MySQL has several paid editions.|
|2.||It is ACID compliant from the ground up.||It is only ACID compliant when suing NDB and InnoDB Cluster Storage engines.|
|3.||Largely SQL compliant||Partially compliant to some of the SQL versions|
|4.||Used for large systems where to write and read speeds are crucial, and data need to be validated.||Used for web-based projects that require a database for data transaction|
In PostgreSQL, table partitioning refers to splitting a large table into smaller sections. PostgreSQL supports list and range partitioning via table heritance. Users have to create each partition as a child table of the master table.
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.
|1.||Microsoft’s relational DBMS||Widely used open source object-relational database management system|
|2.||Implementation language is C.||The implementation language is C++.|
|3.||Supports server is operating systems such as HP-UX, NetBSD, Solaris, Windows, Unix, Linux, and FreeBSD.||Supports only Linux and Windows.|
|4.||Doesn’t has the in-memory capability.||Has in-memory capability.|
|1.||Mostly aid object-relational database management system||open source object-relational database management system|
|2.||The implementation language is C.||Implementation language is C and C++.|
|3.||Server operating systems here are OS X, Linux, Windows, z/OS, AIX, and HP-UX.||Server operating systems here are HP-UX, NetBSD, Solaris, Windows, Unix, Linux, and FreeBSD.|
|4.||More database productivity||Less database productivity|
|5.||Advance security options||Good security support but less compared to Oracle|
|1.||It’s an object-relational database management system.||It uses JSON-like documents to store schema-free data.|
|2.||uses tables, triggers, constraints, roles, stored procedures and views as the core components||Uses Key, Collection, Document, and Value.|
The Multi-Version Concurrency Control or MVCC is a method present in PostgreSQL to handle data consistency when multiple processes are accessing a single table. It is a standard database technique and not limited only to PostgreSQL.
In PostgreSQL, the index is a common way for database performance enhancement. It allows the database server to find the retrieve specific rows faster compared to without index. It also adds overhead to the database system as a whole, so users have to implement them sensibly.