What are the common techniques used to denormalize a database schema?
- Aggregating Tables
- Data Duplication
- Horizontal Partitioning
- Vertical Partitioning
Denormalization involves introducing redundancy into a table or database to improve query performance or simplify data management. Common techniques include data duplication, where selected data is stored in multiple tables for easier retrieval, and aggregating tables, where data from multiple tables is combined into a single table for faster queries.
Scenario: A company regularly performs backups of its DB2 database using the EXPORT utility. However, the size of the backups has become increasingly large, impacting storage and performance. What strategies could the company implement to address this issue?
- Archive Logs
- Implement Compression
- Increase Buffer Pool Size
- Use Parallelism
Implementing compression is an effective strategy to address the issue of large backup sizes when using the EXPORT utility. By enabling compression during the export process, the company can significantly reduce the size of the backup files, thereby saving storage space and improving overall performance. Compression techniques such as zlib or gzip can be applied to the exported data to achieve compression ratios that balance between space savings and processing overhead.
The COUNT() function in DB2 returns the ________ of rows that meet the specified condition.
- Number
- Sum
- Count
- Average
The correct option is "Count". The COUNT() function in DB2 returns the number of rows that meet the specified condition. It is commonly used to count the number of rows in a table that satisfy certain criteria.
The Lock Manager in DB2's architecture ensures ________.
- Buffer management
- Data consistency in multi-user environments
- Data storage and retrieval
- Query optimization
The Lock Manager in DB2 ensures data consistency in multi-user environments by managing locks on data resources. It ensures that transactions execute serially and concurrently without interfering with each other, thus maintaining data integrity and preventing conflicts. Locks are used to control access to data and prevent concurrent transactions from modifying the same data simultaneously, thereby avoiding inconsistencies.
What are the different phases involved in the Reorg process in DB2?
- Analyze, Sort, and Reconstruct
- Data Compression, Statistics Update, Index Optimization
- Index Rebuild, Data Defragmentation, Space Reclamation
- Table Partitioning, Data Archiving, Data Encryption
The Reorg process in DB2 involves multiple phases to ensure data organization and optimization. These phases typically include analyzing the table, sorting the data, and reconstructing the table structure. Additionally, it may involve tasks such as rebuilding indexes, defragmenting data, reclaiming unused space, updating statistics, and optimizing indexes for better performance. Each phase contributes to improving the overall efficiency and performance of the database.
Different editions of DB2 are tailored to meet specific ________ requirements.
- Business
- Hardware
- Regulatory
- Security
Different editions of DB2 are tailored to meet specific business requirements. Each edition of DB2 is designed with a particular set of features and capabilities to address the diverse needs of businesses across various industries and sectors. For instance, enterprise-level editions might offer advanced business intelligence tools, scalability features, and support for large datasets, while smaller editions might focus on basic transaction processing and reporting functionalities suitable for small to medium-sized businesses. Understanding these tailored features helps organizations in selecting the right edition of DB2 that aligns with their specific business requirements and objectives.
The ________ index physically reorganizes the table data based on the indexed column(s).
- Clustered
- Composite
- Non-clustered
- Unique
A clustered index in DB2 physically reorganizes the table data based on the indexed column(s). It arranges the rows in the table in the order of the indexed column(s), resulting in the actual data storage reflecting the index structure. This can significantly improve the performance of queries involving range-based searches or sorting operations since the data retrieval is aligned with the physical order of the rows, reducing the need for extensive disk I/O operations.
What is meant by concurrency control in DB2?
- Ensuring high availability of the DB2 server
- Implementing security measures to control access to DB2 resources
- Managing simultaneous access to data by multiple transactions
- Optimizing SQL queries for performance
Concurrency control in DB2 refers to the management of simultaneous access to data by multiple transactions. It ensures that transactions execute without interfering with each other, maintaining data integrity and consistency. This involves techniques such as locking, timestamping, and multiversion concurrency control to coordinate the execution of transactions and prevent conflicts that could lead to data anomalies.
Scenario: A DBA notices inconsistencies in a DB2 database due to data integrity violations. How can they investigate and resolve these issues effectively?
- Conducting thorough data analysis using DB2 utilities such as CHECK DATA and REPAIR DB
- Reviewing transaction logs to identify the source of integrity violations
- Collaborating with application developers to identify and fix data manipulation errors
- Implementing constraints and triggers to enforce data integrity at the database level
Option 1: Conducting thorough data analysis using DB2 utilities such as CHECK DATA and REPAIR DB enables the DBA to identify and resolve inconsistencies effectively. These utilities can help in identifying corrupt data pages, missing rows, or inconsistencies in indexes. This method ensures that the database remains consistent and reliable.
In DB2, a user-defined function can be created using the ________ statement.
- CREATE FUNCTION
- DECLARE FUNCTION
- DEFINE FUNCTION
- MAKE FUNCTION
User-defined functions in DB2 are created using the CREATE FUNCTION statement. This statement allows developers to define custom functions that can perform specific tasks and can be reused across multiple queries. Functions created using this statement can enhance code modularity and maintainability.