Below are Some Important DB2 UDB DBA Inter
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Question 1: What are the different recovery models available in SQL Server? Explain each one. Answer: SQL Server offers three recovery models: Simple, Full, and Bulk-Logged.
Simple: It allows minimal logging and only supports full backups. It's suitable for databases with non-critical data where data loss is acceptable.
Full: It provides full backups and transaction log backups, allowing point-in-time recovery. It's suitable for critical databases where data loss is unacceptable.
Bulk-Logged: Similar to the Full model but reduces the logging of certain bulk operations. Used when bulk operations are performed infrequently.
Question 2: What is SQL Server AlwaysOn Availability Groups? Answer: AlwaysOn Availability Groups is a high-availability and disaster recovery solution that provides database-level protection. It allows you to create groups of databases that fail over together, ensuring minimal downtime in case of a server or database failure. Question 3: Explain the difference between clustered and non-clustered indexes. Answer: A clustered index determines the physical order of data rows in a table and defines the way data is stored on disk. A table can have only one clustered index. A non-clustered index doesn't affect the physical order of data but creates a separate data structure that points to the data rows. A table can have multiple non-clustered indexes. Question 4: How do you optimize a query that is running slowly? Answer: Several techniques can be used to optimize slow-running queries:
Indexing: Ensure proper indexes are in place to speed up data retrieval.
Query Rewriting: Modify the query to use more efficient syntax.
Updating Statistics: Keeping statistics up-to-date helps the query optimizer make better decisions.
Query Execution Plan: Analyze the execution plan to identify bottlenecks and inefficiencies.
Normalization: Ensure the database schema is properly normalized to reduce data redundancy.
Caching: Use caching mechanisms to store frequently accessed data.
Question 5: Explain the concept of ACID properties in a database. Answer: ACID stands for Atomicity, Consistency, Isolation, and Durability, which are properties that ensure the reliability of database transactions:
Atomicity: Ensures that transactions are treated as a single unit, either fully completed or fully rolled back.
Consistency: Guarantees that a transaction brings the database from one valid state to another, maintaining data integrity.
Isolation: Transactions are executed independently and aren't affected by the actions of other transactions until they're completed.
Durability: Once a transaction is committed, its changes are permanent and survive system crashes or failures.
Question 6: What is the purpose of the SQL Server Agent service? Answer: SQL Server Agent is responsible for scheduling and automating tasks such as backups, database maintenance, and running jobs. Question 7: Describe the differences between a primary key and a unique key. Answer: Both ensure uniqueness, but a primary key also enforces NOT NULL, while a table can have only one primary key but multiple unique keys. Question 8: What is a deadlock in SQL Server, and how can you prevent it? Answer: A deadlock occurs when two or more transactions are waiting for each other to release resources. Prevention methods include proper indexing, minimizing transaction duration, and using the READ COMMITTED isolation level. Question 9: What is SQL Server Profiler used for? Answer: SQL Server Profiler is a tool for capturing and analyzing SQL Server events and queries to troubleshoot performance issues. Question 10: Explain the concept of database mirroring in SQL Server. Answer: Database mirroring is a high-availability feature that involves maintaining a copy of a database on a separate server to ensure data redundancy and failover capabilities. Question 11: How does Transparent Data Encryption (TDE) work in SQL Server? Answer: TDE encrypts the data at the file level, ensuring that the entire database—including backups and transaction logs—is encrypted. Question 12: What is a collation in SQL Server? Answer: A collation defines how character data is stored and compared in the database. It includes rules for sorting and comparing characters. Question 13: How do you move the system databases in SQL Server to a new location? Answer: Use the SQL Server Configuration Manager to change the startup parameters and specify the new location for system database files. Then restart the SQL Server instance. Question 14: Explain the difference between UNION and UNION ALL in SQL. Answer: UNION returns distinct rows from combined result sets, while UNION ALL returns all rows, including duplicates. Question 15: What are SQL Server Agent jobs, and how do you create them? Answer: SQL Server Agent jobs are automated tasks scheduled to run at specified intervals. They can include T-SQL scripts, SSIS packages, or other commands. You can create them using SQL Server Management Studio. Question 16: What is the purpose of the SQL Server Log Shipping feature? Answer: Log Shipping is used for disaster recovery by maintaining a secondary copy of the database on another server, kept up-to-date by continuously applying transaction log backups. Question 17: Explain the purpose of the CHECKDB command in SQL Server. Answer: CHECKDB is used to check the integrity of a database by scanning its physical and logical structures, identifying any inconsistencies. Question 18: How can you monitor SQL Server performance using DMVs (Dynamic Management Views)? Answer: DMVs provide insights into SQL Server performance metrics, query execution statistics, memory usage, and more. Queries against these views can help diagnose performance issues. Question 19: What is the purpose of the tempdb database in SQL Server? Answer: The tempdb database is used to store temporary objects, temporary tables, and other transient data used during query processing and temporary operations. Question 20: Describe the differences between a clustered and a non-clustered index in terms of storage. Answer: In a clustered index, data rows are stored in the same order as the index. In a non-clustered index, data rows are stored separately from the index structure. Question 21: How can you monitor and manage SQL Server resources to optimize performance? Answer: Use SQL Server's Resource Governor to allocate resources among different workloads and prioritize resource usage. Question 22: Explain the concept of database snapshots in SQL Server. Answer: A database snapshot is a read-only, static view of a database at a specific point in time. It's useful for reporting or reverting changes. Question 23: How do you configure SQL Server to use SSL encryption for connections? Answer: You need to install an SSL certificate on the SQL Server instance and then configure the server to enable SSL encryption for incoming connections. Question 24: What is the purpose of the SQL Server error log? Answer: The SQL Server error log contains information about errors, warnings, and informational messages related to SQL Server operations. Question 25: Explain the concept of a distributed transaction in SQL Server. Answer: A distributed transaction involves multiple servers and databases, ensuring that a transaction either commits on all involved servers or rolls back on all of them. Question 26: What is the purpose of the SQL Server Integration Services (SSIS) package configuration? Answer: SSIS package configuration allows you to parameterize and externalize package settings, making them more flexible and maintainable. Question 27: Describe the process of restoring a database from a backup in SQL Server. Answer: To restore a database, you need a valid backup and use the RESTORE command. You can specify options like WITH NORECOVERY or WITH RECOVERY depending on the desired state of the database after the restore. Question 28: How do you enable and configure SQL Server's Always Encrypted feature? Answer: Always Encrypted uses cryptographic algorithms to encrypt sensitive data at the client side and store encrypted data in the database. You configure it by specifying column encryption keys and enabling the feature in the connection string. Question 29: What are the system databases in SQL Server, and what is their purpose? Answer: System databases include master, model, msdb, and tempdb. They store essential system and configuration information for the SQL Server instance. Question 30: Explain the concept of partitioning in SQL Server. Answer: Partitioning involves splitting a table or index into smaller, manageable pieces called partitions. This can improve performance and manageability of large datasets. Question 31: How can you perform a point-in-time recovery using transaction log backups? Answer: You can restore a full backup followed by sequential transaction log backups up to the desired point in time using the RESTORE command with the NORECOVERY option. Question 32: What is contained database authentication in SQL Server? Answer: Contained databases store all user authentication and authorization information within the database itself, making it more self-contained and portable. Question 33: How can you identify and troubleshoot long-running queries in SQL Server? Answer: You can use tools like SQL Server Profiler, Extended Events, or Query Store to identify slow queries. Analyzing query execution plans, indexes, and statistics can help with troubleshooting. Question 34: Describe the process of upgrading a SQL Server instance to a newer version. Answer: The process involves backing up databases, installing the new SQL Server version, and then restoring the databases to the new instance. Compatibility issues and deprecated features should be addressed. Question 35: What is the purpose of the SQL Server Reporting Services (SSRS) service? Answer: SSRS is used to create, deploy, and manage reports for data analysis and visualization. Question 36: How can you monitor SQL Server performance using Extended Events? Answer: Extended Events allow you to capture low-level events and performance metrics for troubleshooting and monitoring purposes. Question 37: What is the purpose of the Resource Database in SQL Server? Answer: The Resource Database is a read-only system database that stores system objects and metadata used by SQL Server. Question 38: Explain the concept of Always Encrypted with secure enclaves in SQL Server. Answer: Always Encrypted with secure enclaves allows sensitive data to be encrypted in a secure enclave, providing an extra layer of security. Question 39: How do you enable and configure SQL Server Auditing? Answer: SQL Server Auditing allows you to track and log events at the database level. It's configured using SQL Server Management Studio or T-SQL scripts. Question 40: What are the differences between a scalar function and a table-valued function in SQL Server? Answer: A scalar function returns a single value, while a table-valued function returns a table with multiple rows.
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