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Table of contents
1.
Introduction
2.
What is Oracle?
3.
Oracle DBA Interview Questions for Freshers
3.1.
1. What do you mean by OracleDB?
3.2.
2. What is a database?
3.3.
3. What is the use of a database management system?
3.4.
4. What is the use of indexes in the database?
3.5.
5. How does the B-tree index work?
3.6.
6. What are two types of storage on which Oracle database architecture depends?
3.7.
7. What provides the information about the segments in DBA?
3.8.
8. What is the use of v$log in DBA?
3.9.
9. What do you mean by tablespace?
3.10.
10. What do you mean by segment?
4.
Oracle DBA Interview Questions for Intermediate
4.1.
11. How many physical components are there in the Oracle database? Name them.
4.2.
12. How is physical storage different from logical storage?
4.3.
13. What are various oracle database objects?
4.4.
14. What is database normalization?
4.5.
15. What are various normalization forms?
4.6.
16. What does the logical structure of a disk resource include?
4.7.
17. How are data blocks and extent different from each other?
4.8.
18. What is the use of rollback segments?
4.9.
19. Name the components of the oracle disk.
4.10.
20. What tools can be used in assisting performance monitoring that is provided by Oracle?
5.
Oracle DBA Interview Questions for Experienced
5.1.
21. What are the benefits of Oracle database administration?
5.2.
22. What tasks does the Oracle database administrator include?
5.3.
23. How are clustered and non-clustered indexes different from each other?
5.4.
24. What are the responsibilities of database administrators?
5.5.
25. Which dictionary tables are used to monitor the database space?
5.6.
26. How can we find the total size of the database?
5.7.
27. How are recovering and restoring a database different from each other?
5.8.
28. On what recovery catalog stores information?
5.9.
29. What are the main features of Oracle database security management?
5.10.
30. How first normalization form is different from the second normalization form?
5.11.
31. Briefly explain the purpose of password files in Oracle DBA.
5.12.
32. What is a trace file?
5.13.
33. What do you understand about Oracle home inventory?
5.14.
34. What is a deadlock in Oracle DBA?
5.15.
35. What is the purpose of the ANALYZE command?
5.16.
36. What do you understand by scope parameter?
5.17.
37. Why is it important for LGWR (Log Writer) to come before DBWR (Database Writer)?
5.18.
38. Explain SNIPPED sessions in an Oracle database.
5.19.
39. How do you convert the archiving mode of a database from NO ARCHIVELOG to ARCHIVELOG?
5.20.
40. What is the importance of bind variables in Oracle DBA?
6.
Frequently Asked Questions
6.1.
What are the challenges faced in Oracle DBA?
6.2.
What are the daily activities of Oracle DBA?
6.3.
How do you handle errors in Oracle?
7.
Conclusion
Last Updated: Mar 27, 2024
Medium

Top 40 Oracle DBA Interview Questions & Answers (2023)

Introduction

Are you preparing for interviews? Are you especially looking for a role in information technology? If yes, then you must know about Oracle database administration(DBA). You must know a few major Oracle DBA interview questions in order to get selected.

oracle dba interview questions

In this article, we will discuss Oracle DBA. We will also be discussing Oracle DBA interview questions. We will see questions on each category that is easy, medium, and hard. Moving forward, let’s discuss easy-level Oracle DBA interview questions.

What is Oracle?

Oracle is a popular technology company that is used to develop data management systems and other software services. Oracle DBA is one important product of the company that is used to store and manage data in many other organizations.

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Oracle DBA Interview Questions for Freshers

1. What do you mean by OracleDB?

OracleDB is a database management system. This system helps in managing the database. It is used in organizing, managing, and storing large proportions of information.

2. What is a database?

A Database is a collection of data records, mainly in the form of tables, that contain information. It allows us to access and update data records easily. Databases are helpful in large organizations for managing HRMS(Human Resource Management System) and so on.

3. What is the use of a database management system?

The database management system is a collection of programs that help in storing and retrieving data from the database. DBMS consists of programs that are helpful in manipulating databases. The database management system works in such a way that it acts as an interface between the database and the user. It allows users to create, read, update and delete data from the database.

4. What is the use of indexes in the database?

In the database, the indexes are used to access and retrieve data easily. Indexes play an important role in improving the performance of the queries. They allow the database to find out any specific row and column easily and perform the task.

5. How does the B-tree index work?

The B-tree index works in such a way that the database sort all the values that are present in the table. And then, this data is stored in a B-tree data structure. This data structure contains pointers across each row in a table. All the values in this structure are stored in such a way that searching and retrieving data becomes very easy.

6. What are two types of storage on which Oracle database architecture depends?

The two types of storage on which Oracle database architecture depends are:

  • Physical Storage: Physical storage can be defined as the storage medium where the database gets stored. For example, hard drives, and so on.
     
  • Logical Storage: Logical storage can be defined as a way where the data is stored in the database. For example, tables, views, indexes, and so on.

7. What provides the information about the segments in DBA?

The Dba_segments is used to provide the segment information in DBA. The segments can be defined as a logical storage units. They consist of data, such as indexes, tables, partitions, and so on.

8. What is the use of v$log in DBA?

The v$log is helpful in providing information about redo log files. The redo log files play an important role as it allows data to recover back in case of system errors and failures.

9. What do you mean by tablespace?

The tablespace can be defined as the logical storage unit. It allows grouping more than on datafiles together. It is helpful in organizing and allocating the storage for database objects.

10. What do you mean by segment?

The segments can be defined as a logical storage units. They consist of data, such as indexes, tables, partitions, and so on. It is managed by DBMS. The DBMS automatically creates segments in order to store the object’s data. 

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Oracle DBA Interview Questions for Intermediate

11. How many physical components are there in the Oracle database? Name them.

There are five physical components in the Oracle database. The physical components are:

  • Data files
     
  • Control files
     
  • Redo log files
     
  • Password files
     
  • Parameter files

12. How is physical storage different from logical storage?

The Oracle database architecture depends upon physical and logical storage. The physical storage includes files in the database. Whereas logical storage consists of segments, blocks, tablespaces, and so on.

13. What are various oracle database objects?

The oracle database objects are as follows.

  • Tables
     
  • Tablespaces
     
  • Indexes
     
  • Sequences
     
  • Views

14. What is database normalization?

Database normalization can be defined as the process by which the data is organized in the database. Normalization helps in reducing the data redundancy. It also improves data integrity. With normalization, the database becomes more flexible as the inconsistent dependency is removed.

15. What are various normalization forms?

The various normalization forms are.

  • First Normal Form (1NF)
     
  • Second Normal Form (2NF)
     
  • Third Normal Form (3NF)
     
  • Boyce-Codd Normal Form (BCNF)
     
  • Fourth Normal Form (4NF)
     
  • Fifth Normal Form (5NF)

16. What does the logical structure of a disk resource include?

The logical structure of a disk resource includes the following.

  • Data block
     
  • Extent
     
  • Tablespace
     
  • Segment


17. How are data blocks and extent different from each other?

The data blocks and extents are the storage units. They allow storing the information in the database. They only vary in the size of the data they hold. The data block is the smallest unit of logical storage. So, it has specified space. Whereas the extent is a set of data blocks. It can store one or more than one data block. The extent is allocated to segments as a unit.

18. What is the use of rollback segments?

The rollback segment is used to roll back the transactions. A database can include one or more than one rollback segment. It is also helpful while implementing the mechanism for database transaction control. As it allows for storing the undo information, which was generated while the transactions were executing in the database.

19. Name the components of the oracle disk.

The components of the oracle disk include.

  • Redo Log Files.
     
  • Parameter files.
     
  • Control files.
     
  • Data files.
     
  • Password files.

20. What tools can be used in assisting performance monitoring that is provided by Oracle?

There are many tools that can be used in assisting performance monitoring that is provided by Oracle. A few of them are as follows.

  • Automated Database Diagnostics Monitor.
     
  • Oracle Enterprise Manager.
     
  • Automatic Workload Repository.


Moving forward, let’s discuss hard-level oracle dba interview questions.

Oracle DBA Interview Questions for Experienced

21. What are the benefits of Oracle database administration?

There are many benefits of Oracle database administration. A few of them are as follows.

  • Oracle DBA helps in managing the database.
     
  • It allows server connectivity.
     
  • It helps in maintaining the database easily.
     
  • It includes streamlined tasks, backup and recovery, and so on.

22. What tasks does the Oracle database administrator include?

There are many tasks that Oracle DBA includes. A few of them are as follows.

  • We can install oracle software using oracle database administrator.
     
  • We can easily upgrade software and databases using Oracle DBA.
     
  • The database storage is managed and maintained by Oracle DBA.
     
  • Oracle DBA allows starting up and shutting down the database.

23. How are clustered and non-clustered indexes different from each other?

In the database, the indexes are used to access and retrieve data easily. Indexes play an important role in improving the performance of the queries. They allow the database to find out any specific row and column easily and perform the task. The clustered and non-clustered indexes are the types of indexes. They only vary in the way they store the information. The table is physically stored in the clustered index. In a clustered index, the records are stored in order. Therefore we can say that it includes only a single clustered index. Whereas In a non-clustered index, logical sorting takes place. Here the row order is not similar to the physical order of the actual data.

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24. What are the responsibilities of database administrators?

There are many responsibilities of database administrators. A few of them are as follows.

  • The database administrator helps in keeping the database secure.
     
  • DBA improves the performance of the database.
     
  • The DBA helps in managing database objects and storage.
     
  • The DBA allows the creation of users, removal of existing users, modification of user permissions, and so on at the administration level.

25. Which dictionary tables are used to monitor the database space?

The dictionary tables that are used to monitor the database space are as follows.

  • DBA_FREE_SPACE.
     
  • DBA_SEGMENTS.
     
  • DBA_DATA_FILES.

26. How can we find the total size of the database?

The information about the size of the database can be found by using the following views.

  • Dba_segments
     
  • v$log
     
  • Dba_data_files
     

Dba_segments: The Dba_segments is used to provide the segment information in DBA. The segments can be defined as a logical storage units. They consist of data, such as indexes, tables, partitions, and so on.

v$log: The v$log is helpful in providing information about redo log files. The redo log files play an important role as it allows data to recover back in case of system errors and failures.

Dba_data_files: The Dba_data_files is used to provide information about the space allocation to datafiles, which is for permanent tablespaces.

27. How are recovering and restoring a database different from each other?

Recovering and restoring a database are correlated, but they vary in the processes they use to recover the database in case of data loss and failures. Recovering a database helps to recover the changes that are not backed up successfully. Whereas restoring a database helps in copying backup files from the hard disk to the restoration location. 

28. On what recovery catalog stores information?

The recovery catalog stores information on.

  • Stored scripts
     
  • Backup history
     
  • Data files
     
  • Redo logs that are archived, and so on.

29. What are the main features of Oracle database security management?

There are many features of Oracle database security. A few of them are as follows. 

  • Oracle database security helps to control accessing data.
     
  • It authenticates the user. So that non-restricted users cannot access the data easily.
     
  • Oracle database keeps the data in the database safe.

30. How first normalization form is different from the second normalization form?

The difference between first and second normalization are as follows.

First Normalization

Second Normalization

In first normalization, the attributes of the table cannot hold multiple values. In second normalization, all the non-key attributes have a dependency on the primary key.
The atomicity of the table in the first normalization form is 1. The atomicity is not related to second normalization.
First normalization allows eliminating repeating groups. Second normalization allows eliminating partial dependencies.

31. Briefly explain the purpose of password files in Oracle DBA.

Password files in Oracle DBA store the passwords and other credentials of remote and local users of the database. Password files add an extra layer of authentication. This helps in controlling the access of SYSDBA and SYSOPER users to the database. This increases security as only authorized users can perform tasks on the database. 

32. What is a trace file?

In Oracle, a trace file is a log file that contains information about the activities that occur when an SQL statement is run. This, in turn, helps in identifying and fixing bugs and other database-related problems. The ALTER SESSION command can be used to enable tracing for a user session.

33. What do you understand about Oracle home inventory?

Oracle Home inventory is the folder where the Oracle software is installed. It contains the list of all files and other database objects that are installed during the installation of Oracle on a computer. Oracle home inventory manages and maintains the Oracle software.

34. What is a deadlock in Oracle DBA?

A deadlock occurs when two or more users try to change the rows in a table, but each action needs the other user to release its locked rows first. This reduces the server's performance, which is fixed when either of the actions is finished, or the users stop the actions manually. When the actions are stopped, the locked rows get freed, and the deadlock is resolved.

35. What is the purpose of the ANALYZE command?

The ANALYZE command is used to collect the statistics about the database objects like the tables, indexes, clusters, etc. This, in turn, helps the database optimizer to make better decisions. It is also used to get a table's linked and imported row. Besides, the Analyser command also checks if the structure of the database is correct.

36. What do you understand by scope parameter?

The scope parameter states how changes to a value affect the database while using the server parameter file or the file. We can change the values of parameters with three different scopes:

  • Spfile scope: Here, the changes occur after the reboot of the next database.
  • Memory scope: Here, the changes are updated immediately in memory but are lost after the database is restarted.
  • Both scopes: Changes are updated immediately in the memory and remain even after the database is restarted. 

37. Why is it important for LGWR (Log Writer) to come before DBWR (Database Writer)?

LGWR comes before DBWR because the Recordkeeping of transactions is always more important than their processing and recovery. The repeated logs of LGWR store a record of all changes that are made in the database. This allows the recovery of transactions even in cases of power failure. The DBWR writes the changes in the data to the storage.

38. Explain SNIPPED sessions in an Oracle database.

SNIPPED sessions occur when active connections exceed a fixed time limit. When a client crosses this limit, Oracle stops its tasks at the database level. The OS-level process still continues. This helps in managing the long sessions in the database and prevents them from using extra resources, thus increasing the performance of the system.

39. How do you convert the archiving mode of a database from NO ARCHIVELOG to ARCHIVELOG?

To convert the archiving mode of a database from NO ARCHIVELOG to ARCHIVELOG, we should first shut down the database. Prepare a backup for the safety of the database. Next, complete the steps needed as per your operating system. Now start a new instance and load the database. It should be noted that the database is not opened yet. Now we can change the archiving mode to ARCHIVELOG.

40. What is the importance of bind variables in Oracle DBA?

Bind variables are important because they enable the efficient execution of plan caching in many database systems. When SQL statements are executed with bind variables, the database stores the execution plan in a cache. Thus if the same SQL statements are executed again but with different values of bind variables, the database can reuse the cached execution plan. This, in turn, saves a lot of time and memory.

Frequently Asked Questions

What are the challenges faced in Oracle DBA?

The challenges faced on Oracle DBA is that it is very complex for beginners. Also, sometimes data backups in Oracle DBA increase the load in CPUs and memory usage which in turn decreases the performance of the database.

What are the daily activities of Oracle DBA?

The daily activities of oracle DBA involves installing the software, creating databases, and performing updates.  It also manages the security of data, storing of data and managing the schema of the database.

How do you handle errors in Oracle?

To handle errors in Oracle we can use the routines which are also known as exception handlers. Whenever there is an error an exception is raised that lets developers perform the required fixes.

Conclusion

In this article, we have discussed easy, medium, and hard Oracle DBA interview questions. To learn more, you can check out our other articles:

We hope this article helped you in learning Oracle DBA interview questions. You can read more such articles on our platform, Coding Ninjas Studio. You will find articles on almost every topic on our platform. Also, you can practice coding questions at Coding Ninjas to crack good product-based companies. For interview preparations, you can read the Interview Experiences of popular companies

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