In an ERD, a double-lined rectangle represents a(n) ________ entity.
- Dependent
- Derived
- Strong
- Weak
In an ERD, a double-lined rectangle represents a strong entity. A strong entity is one that exists independently of other entities and has its own unique identifier. It is not dependent on any other entity for its existence.
The VARIANCE() function in DB2 returns the ________ of the values in a column.
- Variance
- Standard Deviation
- Mean
- Median
The correct option is 1. The VARIANCE() function in DB2 calculates the variance of the values in a column, which represents how much the values in the column deviate from the mean value of the column.
What are the key considerations for selecting an encryption algorithm in DB2?
- Compression ratio, backup speed, transaction throughput
- Database schema complexity, indexing efficiency, storage overhead
- Network latency, query optimization, user authentication
- Strength of encryption, performance impact, compatibility with regulatory requirements
When selecting an encryption algorithm in DB2, key considerations include the strength of encryption, performance impact, and compatibility with regulatory requirements. These factors ensure data security and compliance.
Explain the concept of transitive dependency in the context of normalization.
- A field depends on another field which is not the primary key
- A field depends on the primary key through another non-prime attribute
- A non-prime attribute depends on another non-prime attribute
- A primary key depends on a non-prime attribute
Transitive dependency occurs in a relation when a non-prime attribute depends on another non-prime attribute, which, in turn, depends on the primary key. This dependency chain indicates that the non-prime attribute is indirectly dependent on the primary key through another non-prime attribute, violating the rules of normalization.
Scenario: A company is designing an ERD for its HR system. They identify a scenario where an employee may have multiple dependents, but a dependent can only belong to one employee. What type of relationship does this represent in the ERD?
- Many-to-Many
- None of the above
- One-to-Many
- One-to-One
This scenario illustrates a One-to-Many relationship in the ERD. It implies that one employee can have multiple dependents, but each dependent can only be associated with one employee.
Scenario: A database designer is creating an ERD for a banking system. They encounter a scenario where a customer may have multiple accounts, but an account can only belong to one customer. What type of relationship does this represent in the ERD?
- Many-to-Many
- None of the above
- One-to-Many
- One-to-One
This scenario represents a One-to-Many relationship in the ERD. In a One-to-Many relationship, one entity instance can be associated with multiple instances of another entity, but each instance of the second entity can only be associated with one instance of the first entity. In this case, one customer can have multiple accounts, but each account can only belong to one customer.
What does DB2 offer in terms of scalability?
- Automatic scaling, Manual scaling, Elastic scaling
- Dynamic resizing of resources, No support for scaling
- Horizontal scalability, Vertical scalability, Limited scalability, No scalability
- Scalable storage, Scalable processing power, Scalable memory
DB2 provides both horizontal and vertical scalability. Horizontal scalability involves adding more machines or nodes to a system to handle increased load, while vertical scalability involves increasing the resources (such as CPU, memory, or disk) on a single machine to accommodate growth. This flexibility enables DB2 to handle varying workloads efficiently.
Scenario: A developer is designing an application that requires high concurrency in DB2.
- Increase the transaction isolation level to ensure stronger consistency.
- Minimize transaction duration by breaking down tasks into smaller units.
- Use a deadlock detection mechanism and implement retry logic.
- Utilize Serializable isolation level to prevent concurrency-related issues.
In a high-concurrency environment, minimizing transaction duration by breaking tasks into smaller units can reduce the likelihood of conflicts and deadlocks. By keeping transactions short-lived, the system can handle more concurrent requests, optimizing throughput. This approach helps in avoiding contention for resources and ensures efficient utilization of system resources.
Analyzing and optimizing the ________ can lead to better overall DB2 performance.
- Application code
- Buffer pools
- Database configuration
- Locking mechanisms
Analyzing and optimizing the database configuration, including parameters such as buffer pool sizes, can lead to better overall DB2 performance.
Which data format is commonly used for representing hierarchical data structures in DB2?
- CSV
- JSON
- TXT
- XML
JSON (JavaScript Object Notation) is commonly used for representing hierarchical data structures in DB2. JSON provides a lightweight and easy-to-read format for organizing and exchanging data, making it well-suited for applications that require hierarchical data representation, such as web services and NoSQL databases.