Introduction to DBA interview Questions And Answer
Preparing for a job interview in DBA. I am sure you want to know the most common 2021 DBA Interview Questions and answers that will help you crack the DBA interview with ease. Below is the list of top DBA Interview Questions and answers to your rescue.
If you are interested in making your career as a DBA, Database Administrator, then you are at the right place. We are going to discuss the important DBA interview questions every aspiring candidate should know.
DBA Interview Questions And Answer
Below are the 5 important 2021 DBA Interview Questions and answers that are frequently asked in an interview.
1. Explain Oracle and its database?
Answer:
Oracle in itself is a company. It is a DB server that is used to manage data in a structured way and ensures that the same set of data is being accessed in a concurrent manner. All this is done to ensure high performance is never compromised. A DB server prevents unauthorized access to data and provides mechanisms for failure recovery. Oracle provides its solutions to create and manage its database. It consists of logical and physical structures in which user, system, and control information is saved. In a nutshell, software that runs a physical database and Oracle is called Oracle database system together. A database buffer cache is used to store the data in memory. The redo is used for logging track and stores the changes made to DB.
2. Explain the role of DBA and its characteristics?
Answer:
DBA has the right to create new users, update existing users and modify environment variables or any other kind of privilege assigned to the users. The roles include:
- Manage database storage
- Manage Schema objects
- Administer security and users
- Manage and monitor database performance
- Schedule and automate jobs
- Perform backup and recovery
The characteristics of DBA include:
| Criterion | Result |
| Architecture | Grid Architecture |
| Storage Structure | Logical and Physical |
| ACID based compliance | Fully Compliant |
| Data is stored as | Data extents, blocks, tablespaces and segments |
Let us move to the next DBA Interview Questions.
3. Describe common Oracle Tasks?
Answer:
As you are an Oracle Database Administrator, you can expect yourself to be related to the following tasks:
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- Installing the software
- Create Oracle Databases
- Maintaining and performing regular and scheduled updates to both database and software.
- Starting up, monitoring and closing the database
- Managing and taking care of the database’s storage schemas and structures
- Managing the security of users
- Monitoring and managing user schema functions and objects such as tables, views, and indexes
- Periodic backup and recovery of data in case of data failure and ensure high availability.
- Proactive in monitoring the health and taking appropriate corrective and preventive measures as and when needed
Performance tuning and management of a small, midsize database environment is generally an expectation. If you are told to handle large enterprise-level software and databases, the job is divided among a set of DBAs who are then responsible for the execution and planning of all the database management together. In that case, you would not need to worry about being the database administrator as well as managing the security parameters.
4. List down the tools used to administer the database? Explain SQL plus and its operations.
Answer:
The following tools can be used in achieving the goals as a DBA.
•Oracle Universal Installer: This tool is used to install the basic and recommended set of Oracle software. It is used to launch the Database Configuration Assistant (an essential tool for Database) automatically.
•Database Configuration Assistant: DBCA is used to create a new set of a database using pre-defined templates that are provided by Oracle. You are also free to create your own customized set of templates. A preconfigured seed database can be copied, which saves time and effort significantly as customization and generating the database from scratch is not required.
•Database Upgrade Assistant: It is used to guide through the upgrade of an already existing database to a fresh Oracle release.
•Oracle Net Manager: This tool is used to guide through the Oracle Net network-related configurations.
•Oracle Enterprise Manager: The Oracle Enterprise Manager is the tool for your database management. It is a web-based interface that only runs once you have installed the software, created and upgraded the database, tuned and configured the network as per your needs. It is a highly efficient single interface manager. It also provides interfaces for performance advisors and other interfaces related to performance utilities as well. The performance utilities include the ones like recovery Manager and SQL Loader.
SQL Plus is a basic command-line tool developed by the company Oracle. Below are some characteristics of the SQL Plus tool:
•It is a freely distributable software that is shipped along with Oracle Database installations and client installations by default.
•You can find the path of SQL Plus under the “$ORACLE_HOME/bin/” directory only when the Oracle client or software is installed on the computer.
•The executable name in the case of Linux OS sqlplus and sqlplus.exe in the case of Windows OS.
•Oracle Database can be connected with it doing which enables easy access and availability for running executable queries and working on Oracle Database. It has its own set of features and commands, which is used for formatting the output in order to display the results in a neat and presentable way.
Let us move to the next DBA Interview Questions.
5. What is a password file, and what is its need?
Answer:
Database users’ passwords are stored in the data dictionary of the database. When the user wishes to log into the database, the set of usernames and passwords which is provided by him is verified and validated against the set of values already stored in the database for that corresponding value. Once the data seems to match, then the access is granted; otherwise, it is revoked for that particular user. The data dictionary is the part of the database which can be accessed as long as the database is in the opened state. The administrator’s passwords are also stored in the data dictionary. When the database is closed, the data dictionary is inaccessible, and there needs some mechanism to access data at that point in time. To our rescue, the password files come into the picture. It is a separate operating system file that is stored on the disk present outside of the database. The username and passwords with SYSDBA or SYSOPER privileges are stored in the file, and the administrators have the authority to access the password file even if the database is down.
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