Last updated on Nov 16, 2023
Each database requires at least one database administrator (DBA) to administer it. The Oracle DBA is not a one-person job as the system is large and has many users. In these cases, there is a group of DBAs who share responsibilities.
In this article, you can go through the set of Oracle DBA interview questions most frequently asked in the interview panel. This will help you crack the interview as the topmost industry experts curate these at HKR training.
Let us have a quick review of the Oracle DBA interview questions.
Ans:Oracle Database is a comprehensive and sophisticated relational database management system (RDBMS) designed to efficiently handle extensive data storage and retrieval. It distinguishes itself by separating physical and logical structures, allowing for flexible data management and optimized access.
Oracle DBA: Focuses primarily on database management, overseeing streamlined tasks, including maintenance, backup, recovery, and server connectivity. Operates chiefly in backend database management.
Oracle Developer: Concentrates on front-end development, involving a broader spectrum of responsibilities such as coding, UI design, and database development.
Ans: Utilize the “v$pwfile_users” view in SQL. By executing SELECT * FROM v$pwfile_users;, you can access detailed information about each user's privileges in the password file, including USERNAME, SYSDBA, SYSOPER, and SYSASM privileges.
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Ans: A DBA plays a crucial role in database management, responsible for user administration, storage management, security, performance monitoring, and executing backup and recovery protocols.
Ans: Typical tasks include installing Oracle software, database creation and upgrades, storage management, user and security management, performance monitoring, and ensuring robust backup and recovery processes.
Ans: Key objects in Oracle databases include Sequences, Views, Tables, Tablespaces, and Indexes.
Ans: A control file is vital for an Oracle database, containing essential information like the database name, datafile and redo log file locations, database creation timestamp, log sequence number, and checkpoint details.
Ans: Tools for database administration include Oracle Universal Installer, Database Configuration Assistant, Database Upgrade Assistant, Oracle Net Manager, and Oracle Enterprise Manager.
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Ans: Dictionary tables like DBA_FREE_SPACE, DBA_SEGMENTS, and DBA_DATA_FILES are instrumental in monitoring database space.
Ans: EBU (Enterprise Backup Utility) is used for backing up Oracle7 databases. At the same time, RMAN (Recovery Manager) is a more advanced utility introduced in Oracle8 and above, offering enhanced features with no direct upgrade path from EBU.
Ans: Oracle's logical disk structure encompasses Data Blocks, Extents, Tablespaces, and Segments, each serving a specific data organization and storage function.
Ans: The database size can be determined using views such as dba_segments for used space, dba_data_files for datafile space, and v$log for redo log file information.
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Ans: Auditing in Oracle can be categorized into Statement Auditing, Privilege Auditing, and Object Auditing, each tracking different aspects of database usage and access.
Ans: Performance tuning requires a blend of technical expertise and analytical skills, as it involves diagnosing and resolving issues related to process inefficiencies and application scalability.
Ans: Dynamic performance views, also known as V$ views, provide session information. Access is typically granted through the SELECT_CATALOG_ROLE role, available to any Oracle user.
Ans: An ASM (Automatic Storage Management) instance manages disk groups comprising the System's Global Area (SGA) and background processes, essential for efficient database file layout and metadata management.
Ans: ASM Disk Groups are clusters of disks managed by ASM, simplifying database storage and reducing I/O overhead.
Ans: Restoring RMAN involves:
Ans: Instance recovery is an automated process activated upon database restart due to instance failure, safeguarding transactions not recorded on disk.
Ans: Essential files for backup include Database files, Control files, Archived log files, Password files, and INIT.ORA.
Ans: A backup set in the RMAN context is a collection of backup files generated by an RMAN backup command consisting of one or more backup pieces.
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Ans: RMAN architecture comprises the RMAN executable, server processes, channels, target database, recovery catalog database, media management layer, and backups.
Ans: An RMAN backup includes a backup of part or all of a database, resulting from an RMAN backup command, and comprises one or more backup sets.
Ans: A recovery catalog is a repository of metadata used by RMAN for restoration and recovery processes, storing detailed information about data files, backup history, archived redo logs, and more.
Ans: The database Resource Manager limits idle session duration, terminates long-running SQL statements, sets initial login priorities for consumer groups, and specifies the maximum number of active sessions for a consumer group.
Ans: A Resource Plan dictates how resources are allocated among various consumer groups, specifying the percentage of resources like CPU time each group receives.
Ans: Oracle Restart safeguards Database Instances, ASM, Oracle NET Listener, ASM Disk Groups, Database Services, and Oracle Notification Services.
Ans: Tools for database startup include SQL*Plus, Oracle Enterprise Manager, and RMAN.
Ans: Key aspects include:
Ans: Performance can be improved by using direct path load and removing indexes and constraints during load operations.
Ans: Responsibilities include:
Ans: Oracle Grid Architecture offers a cost-effective enterprise information system using grid computing, which enables on-demand connection and disconnection of independent hardware and software components.
Ans: Costly components and high incremental costs characterize large dedicated servers, while Oracle Grid utilizes low-cost modular components, low total costs, and provides enterprise services at a lower price.
Ans: Oracle Grid computing components include Oracle Enterprise Manager and Grid Control, Oracle 10g Database with Real Application Clusters, and ASM Storage Grid.
Ans: The Recoverer process (RECO) in a distributed database configuration automatically resolves failures in distributed transactions.
Ans: Job Queue Processes in Oracle Database automate the execution of PL/SQL processes using background processes and catalog tables.
Ans: Archiver Processes copy redo log files to storage devices post-log switch, functioning only in ARCHIVELOG mode with automatic archiving enabled.
Ans: A Rollback Segment in a database facilitates transaction rollbacks and data recovery.
Ans: A Segment in Oracle is a set of extents allocated for specific data structures and stored in the same tablespace.
Ans: A Synonym in Oracle provides an alternative name for another database object, offering abstraction and protecting applications from changes in base object definitions.
Ans: Server Virtualization in Oracle RAC enables a single database to operate across multiple clustered nodes, pooling processing resources.
Ans: Oracle ASM provides storage virtualization, creating a virtual layer between the database and storage for efficient disk group management.
Ans: Oracle Enterprise Manager 10g's Grid Management feature allows managing multiple systems as a logical group through a single console.
Ans: An Extent in Oracle DB is a set of contiguous Oracle data blocks, forming part of a segment and assigned to store specific information.
Ans: Oracle stores data in Data Blocks, specific byte-sized spaces on disk, serving as the minor logical storage units.
Ans: After reading initialization parameters to determine values, Oracle allocates an SGA (System Global Area) during startup.
Ans: An Oracle Instance comprises the SGA and Oracle processes, coming into existence when the database is started.
Ans: Tools include Oracle SQLPlus and iSQLPlus, Oracle Forms, Reports, Discoverer, Oracle Enterprise Manager, and third-party tools.
Ans: Views in Oracle provide security by restricting access, hiding data complexity, simplifying user queries, and presenting data from a different perspective.
Ans: Oracle operates by starting an instance, establishing client-server connections, executing SQL statements, managing data in the SGA, and maintaining a robust transaction and recovery system.
Ans: The physical structure includes data files, Control Files, Redo Log Files, Archive Log Files, Parameter Files, Alert and Trace Log Files, and Backup Files.
Ans: A Tablespace in Oracle is used for logical data storage, consisting of one or more data files, and can contain objects from different schemas.
Ans: A Dimension in Oracle represents hierarchical relationships between column pairs or column sets, tying child and parent values.
Ans: Oracle's sequence generator provides a sequential series of numbers for generating unique sequential numbers independent of any tables.
Ans: A Control File is a binary file storing crucial database information such as the database name, data files, redo files, creation time, and log sequence number.
Ans: An Index in Oracle is a structure linked to tables or clusters, enhancing SQL statement execution speed by providing a faster access path to table data.
Ans: Shared Server Architecture in Oracle reduces the need for dedicated server processes by routing requests to a shared pool of server processes, optimizing memory use and user support.
Ans: A Transaction in Oracle is a series of SQL statements treated as a single unit, uniquely identified and adhering to ACID properties, encompassing bill pay and purchasing operations.
Ans: The GROUP BY clause in Oracle is used to collect data from different records and group them, with each group having distinct row values for the specified columns.
Ans: The primary function of the redo log is to record all database modifications, enabling the reconstruction of changes and securing rollback data.
Ans: SQL (Str is a language for managing and manipulating data in relational database management systems (RDBMS).
Ans: A Public database link in Oracle provides a shared access path to a remote Oracle Database, available to all users.
Ans: ORDBMS offers benefits like storing complex data types, integrating object-oriented programming languages, SQL query capabilities, and ease of learning.
Ans: The COUNT keyword retrieves the total number of records in a table, including counting NULL values with COUNT(*).
Ans: The SELECT statement retrieves data from database tables, views, or materialized views based on specified SQL query instructions.
Ans: Materialized views, also known as summaries, are used to store and compute aggregated data, such as sales figures, and are crucial in decision-making processes in data centres.
Ans: A Sequence in Oracle is a database object that generates a series of numeric values, primarily used for generating unique table values.
Ans: Data Normalization is reorganizing data in the database to ensure clean, structured, and redundant-free data, facilitating efficient analysis and querying.
Ans: Switching from an init.ora file to a spfile involves creating a spfile from the pfile command and restarting the instance using the spfile.
Ans: Oracle databases utilize four primary backup types:
Ans: Oracle’s Database Writer, or DBWn, is integral to its architecture. It transfers 'dirty' buffers from the database buffer cache to disk. This process is crucial when a server updates a data block, which is read into the cache and marked as 'dirty' for subsequent writing to disk if not found in the buffer cache.
Ans: Creating an Oracle sequence involves specifying:
Ans: Key physical components of an Oracle database include:
Ans: To automate database startup post-server reboot:
Ans: Oracle Database utilizes two synonym types:
Ans: The 'SELECT DISTINCT' keyword retrieves unique records from a table.
Ans: Data files are essential components storing database data, represented as physical files within the OS, uniquely identified and constructed for each tablespace.
Ans: Oracle SQL encompasses:
Ans: The 'ORDER BY' keyword is used for sorting records in a table.
Ans: A data file is unique to a database, with a fixed size post-creation, and links to only one database at a time.
Ans: Redo log files are crucial for database recovery, recording all modifications to facilitate restoration in case of data corruption or loss.
Ans: A parameter file is a configuration file containing various initialization parameters and their values, essential for database operation.
Ans: To identify the Oracle Database version, execute the query 'SELECT * FROM V$VERSION' in the command prompt, which fetches version details from the v$version table.
Ans: Response files, used for streamlined database installations, are created by customizing a template or using the Oracle Universal Installer in record mode, which automatically documents installation steps.
Ans: An Oracle database instance transitions through:
Ans: Oracle database segments include:
Ans: Oracle data base is one of the multi-model database management tools; this tool is developed and marketed by Oracle corporations. The main purpose of using the Oracle database tool is to run any online transaction processing, data warehousing, and work well with mixed database workloads.
Ans: Below is the list of roles and responsibility of any Oracle database Administrator;
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