PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions and Answers Freshers, PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions
Before getting on to the PostgreSQL interview questions, the student must know that the PostgreSQL is a continuously varying field which needs the students as well as professionals to upgrade their skills with the new features and knowledge, to get fit for the jobs associated with PostgreSQL. This post related to PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions and Answers Freshers, PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions will help you let out find all the solutions that are frequently asked in you upcoming PostgreSQL interview.
Over thousands of vacancies available for the PostgreSQL developers, experts must be acquaintance with all the component of PostgreSQL technologies. This is necessary for the students in order to have in-depth knowledge of the subject so that they can have best employment opportunities in the future. Knowing every little detail about PostgreSQL is the best approach to solve the problems linked with problem.
APTRON has spent hours and hours in researching about the PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions and Answers Freshers, PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions that you might encounter in your upcoming interview. All these questions will alone help you to crack the interview and make you the best among all your competitors.
First of all, let us tell you about how the PostgreSQL technology is evolving in today’s world and how demanding it is in the upcoming years. In fact, according to one study, most of the companies and businesses have moved to the PostgreSQL. Now, you cannot predict how huge the future is going to be for the people experienced in the related technologies.
Hence, if you are looking for boosting up your profile and securing your future, PostgreSQL will help you in reaching the zenith of your career. Apart from this, you would also have a lot of opportunities as a fresher.
These questions alone are omnipotent. Read and re-read the questions and their solutions to get accustomed to what you will be asked in the interview. These PostgreSQL interview questions and answers will also help you on your way to mastering the skills and will take you to the giant world where worldwide and local businesses, huge or medium, are picking up the best and quality PostgreSQL professionals.
This ultimate list of best PostgreSQL interview questions will ride you through the quick knowledge of the subject and topics like Transactions and Concurrency, Performance Tuning. This PostgreSQL interview questions and answers can be your next gateway to your next job as a PostgreSQL expert.
These are very Basic PostgreSQL Interview Questions and Answers for freshers and experienced both.
Q1: What Is Postgresql?
A1: This is regarded as one of the most successful open source database in the world. This is also used to create advanced applications. This relies on Object relational database management system. Familiarity with UNIX and Linux can be an added advantage while using PostgreSQL.
Q2: State Some Of The Advanced Features Of Postgresql?
A2: These are the following features which are present in PostgreSQL they are
1) Object relational database
2) Extensibility and support for SQL
3) Database validation and flexible API
4) Procedural languages and MVCC
5) Client server and WAL.
Q3: Explain About Write Ahead Logging?
A3: This feature increases the reliability of the database by logging changes before any changes or updations to the data base. This provides log of database incase of a database crash. This helps to start the work from the point it was discontinued.
Q4: Explain About Multi Version Concurrency Control?
A4: Multi version concurrency control or MVCC is used to avoid unnecessary locking of the database. This removes the time lag for the user to log into his database. This feature or time lag occurs when some one else is on the content. All the transactions are kept as a record.
Q5: How to Start The Database Server?
A5:
- /usr/local/etc/rc.d/010.pgsql.sh start
- /usr/local/etc/rc.d/postgresql start
Q6: How To Stop The Database Server?
A6:
- /usr/local/etc/rc.d/010.pgsql.sh stop
- /usr/local/etc/rc.d/postgresql stop
Q7: How To Check Whether Postgresql Server Is Up And Running?
A7:
- /usr/local/etc/rc.d/010.pgsql.sh status
- /usr/local/etc/rc.d/postgresql status?
Q8: What Are The Languages Which Postgresql Supports?
A8: Some of the languages which PostgreSQL supports are as follows:
It supports a language of its own known as PL/pgSQL and it supports internal procedural languages. Pl/pgSQL can be compared to oracle, PL/SQL, etc. Languages such as Perl, Python, TCL can be used as embedded languages.
Q9: Explain About The Command Enable Debug?
A9: This command is used for enabling compilation of all libraries and applications. This process generally slows down the system and it also increases the binary file size. Debugging symbols are present which can assist developers in noticing bugs and problems associated with their script.
Q10: Explain About Functions In Postgresql?
A10: Functions are important because they help the code to be executed on the server. Some of the languages which can program functions for efficient use are PL/pgSQL which is the native language of PostgreSQL. Scripting languages are supported by many languages such as PHP, Perl, Python, etc. PL/R a statistical language can also be used.
Q11: What is maximum size of table in postgresql?
A11: The postgresql has maximum size of table is 32TB.
Q12: What is the option that can be used in PostgreSQL to make transactions see rows affected in previous parts of the transaction?(80% asked Postgresql Interview Questions )
A12: The SQL standard defines four levels of transaction isolation in terms of three phenomena that must be prevented between concurrent transactions. These undesirable phenomena are:
Dirty read
A transaction reads data written by a concurrent uncommitted transaction.
Nonrepeatable read
A transaction re-reads data it has previously read and finds that data has been modified by another transaction (that committed since the initial read).
Phantom read
A transaction re-executes a query returning a set of rows that satisfy a search condition and finds that the set of rows satisfying the condition has changed due to another recently-committed transaction.
Q13: Explain Multi Version concurrency control.
A13: Multi version concurrency control or MVCC is used to avoid unnecessary locking of the database. This removes the time lag for the user to log into his database. This feature or time lag occurs when some one else is on the content. All the transactions are kept as a record.
Q14: How the stats updated in Postgresql?
A14: To update statistics in PostgreSQL explicit ‘vacuum’ call is made. Hope you know the method of doing this. If not let us know and we would help you.Vacuum with the option Analyze is used to update statistics in Postgresql VACUUM ANALYZE ; is the syntax.
Q15: What is write ahead logging in Postgresql?
A15: This feature increases the reliability of the database by logging changes before any changes or updations to the data base. This provides log of database incase of a database crash. This helps to start the work from the point it was discontinued.
Q16: How to start database server in postgresql?
A16:
1. /usr/local/etc/rc.d/010.pgsql.sh start
2. /usr/local/etc/rc.d/postgresql start
Q17: How to stop database server in postgresql?
A17:
1. /usr/local/etc/rc.d/010.pgsql.sh stop
2. /usr/local/etc/rc.d/postgresql stop
Q18: How to change PostgreSQL root user password?
A18:
$ /usr/local/pgsql/bin/psql postgres postgres
Password: (oldpassword)
# ALTER USER postgres WITH PASSWORD ‘tmppassword’;
$ /usr/local/pgsql/bin/psql postgres postgres
Password: (tmppassword)
Changing the password for a normal postgres user is similar as changing the password of the root user. Root user can change the password of any user, and the normal users can only change their passwords as Unix way of doing.
# ALTER USER username WITH PASSWORD ‘tmppassword’;
Q19: How to setup PostgreSQL SysV startup script?
A19:
$ su – root
# tar xvfz postgresql-8.3.7.tar.gz
# cd postgresql-8.3.7
# cp contrib/start-scripts/linux /etc/rc.d/init.d/postgresql
# chmod a+x /etc/rc.d/init.d/postgresql
Q20: How to check whether PostgreSQL server is up and running?
A20:
$ /etc/init.d/postgresql status
Password:
pg_ctl: server is running (PID: 6171)
/usr/local/pgsql/bin/postgres “-D” “/usr/local/pgsql/data”
[Note: The status above indicates the server is up and running]
$ /etc/init.d/postgresql status
Password:
pg_ctl: no server running
[Note: The status above indicates the server is down]
Q21: How to start, stop and restart PostgreSQL database?
A21:
# service postgresql stop
Stopping PostgreSQL: server stopped
ok
# service postgresql start
Starting PostgreSQL: ok
# service postgresql restart
Restarting PostgreSQL: server stopped
ok
Q22: How to create a PostgreSQL Database?
A22:
There are two metods in which you can create two databases.
Method 1: Creating the database in the PSQL prompt, with createuser command.
# CREATE DATABASE mydb WITH OWNER ramesh;
CREATE DATABASE
Method 2: Creating the database in the shell prompt, with createdb command.
$ /usr/local/pgsql/bin/createdb mydb -O ramesh
CREATE DATABASE
* -O owner name is the option in the command line.
Q23: How do I get a list of databases in a Postgresql database?
A23:
# \l [Note: This is backslash followed by lower-case L]
List of databases
Name | Owner | Encoding
———-+———-+———-
backup | postgres | UTF8
mydb | ramesh | UTF8
postgres | postgres | UTF8
template0 | postgres | UTF8
template1 | postgres | UTF8
Q24: How to Delete/Drop an existing PostgreSQL database?
A24:
# \l
List of databases
Name | Owner | Encoding
———-+———-+———-
backup | postgres | UTF8
mydb | ramesh | UTF8
postgres | postgres | UTF8
template0 | postgres | UTF8
template1 | postgres | UTF8
# DROP DATABASE mydb;
DROP DATABASE
Q25: Getting help on postgreSQL commands
A25: \? will show PSQL command prompt help. \h CREATE will shows help about all the commands that starts with CREATE, when you want something specific such as help for creating index, then you need to give CREATE INDEX.
# \?
# \h CREATE
# \h CREATE INDEX
PostgreSQL Conclusion Interview FAQs
We know the list of PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions and Answers Freshers, PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions is overwhelming but the advantages of reading all the questions will maximize your potential and help you crack the interview. The surprising fact is that this PostgreSQL interview questions and answers post covers all the basic of the PostgreSQL technology and you have to check out the FAQs of different components of PostgreSQL too.
However, you will be asked with the questions in the interview related to the above mentioned questions. Preparing and understanding all the concept of PostgreSQL technology will help you strengthen the other little information around the topic.
After preparing these interview questions, we recommend you to go for a mock interview before facing the real one. You can take the help of your friend or a PostgreSQL expert to find the loop holes in your skills and knowledge. Moreover, this will also allow you in practicing and improving the communication skill which plays a vital role in getting placed and grabbing high salaries.
Remember, in the interview, the company or the business or you can say the examiner often checks your basic knowledge of the subject. If your basics is covered and strengthened, you can have the job of your dream. The industry experts understand that if the foundation of the student is already made up, it is easy for the company to educate the employ towards advance skills. If there are no basics, there is no meaning of having learnt the subject.
Therefore, it’s never too late to edge all the basics of any technology. If you think that you’ve not acquired the enough skills, you can join our upcoming batch of PostgreSQL Training in Noida. We are one of the best institute for PostgreSQL in noida which provide advance learning in the field of PostgreSQL Course. We’ve highly qualified professionals working with us and promise top quality education to the students.
We hope that you enjoyed reading PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions and Answers Freshers, PostgreSQL Interview Questions and Answers, PostgreSQL Interview Questions and all the FAQs associated with the interview. Do not forget to revise all the PostgreSQL interview questions and answers before going for the PostgreSQL interview. In addition to this, if you’ve any doubt or query associated with PostgreSQL, you can contact us anytime. We will be happy to help you out at our earliest convenience. At last, we wish you all the best for your upcoming interview on PostgreSQL Technology.
