Scenario: A company has employees and projects. An employee can work on multiple projects, and a project can have multiple employees working on it. Which type of relationship would you use to represent this scenario in an ERD?
- Many-to-Many
- Many-to-One
- One-to-Many
- One-to-One
In this scenario, a Many-to-Many relationship is appropriate. This allows each employee to work on multiple projects, and each project to have multiple employees associated with it. It involves a junction table to manage the relationship.
What is a key characteristic of document databases in terms of schema flexibility?
- Dynamic schema
- Fixed schema
- Relational schema
- Semi-structured schema
A key characteristic of document databases is their dynamic schema. Unlike traditional relational databases with fixed schemas, document databases allow for flexible schema designs where each document can have its own unique structure. This flexibility accommodates evolving data requirements and simplifies the development process.
What factors should be considered when choosing the appropriate Slowly Changing Dimensions (SCD) technique for a data warehouse?
- Availability of primary keys
- Database normalization level
- Number of tables in the database
- Volume of data changes, Query performance, and Data storage requirements
Choosing the appropriate SCD technique involves considering factors such as the volume of data changes, query performance, and data storage requirements. Each type of SCD has its strengths and weaknesses, and the decision should align with the specific needs and characteristics of the data warehouse environment.
_______ techniques in Dimensional Modeling aim to improve query performance by pre-calculating and storing aggregated data.
- Aggregation
- Indexing
- Normalization
- Partitioning
Aggregation techniques in Dimensional Modeling involve pre-calculating and storing aggregated data to enhance query performance. This reduces the need for complex computations during queries, making analytical processing faster and more efficient in data warehouses.
_______ is the process of physically grouping related data together to improve query performance and reduce disk I/O.
- Data Clustering
- Data Encryption
- Data Serialization
- Data Validation
Data Clustering involves physically grouping related data together in storage. This process helps improve query performance by reducing the need for extensive disk I/O operations when retrieving related data. It enhances the efficiency of data retrieval operations, especially in scenarios where related data is commonly accessed together.
Which type of dimension change captures historical data without overwriting existing records?
- Type 1
- Type 2
- Type 3
- Type 4
Type 2 dimension change captures historical data without overwriting existing records. It adds new records for each change, including a surrogate key and an effective date range, allowing for historical analysis while preserving the original data.
How do NoSQL databases handle consistency in distributed systems compared to traditional relational databases?
- Emphasizing centralized control
- Relying on eventual consistency
- Using ACID properties
- Utilizing distributed transactions
NoSQL databases often rely on eventual consistency in distributed systems compared to traditional relational databases. Unlike traditional databases that emphasize strong consistency through distributed transactions and ACID properties, NoSQL databases prioritize low-latency operations and high availability, accepting temporary inconsistencies that will eventually be resolved.
The _______ constraint allows you to define a condition that must be met for the data to be valid.
- Check
- Integrity
- Referential
- Validation
The Check constraint in a database allows you to define a condition or expression that must be satisfied for the data to be considered valid. It is used to ensure that data adheres to specific criteria, providing data integrity at the column level.
What is the primary goal of clustering in database management?
- To group similar data together
- To improve database backups
- To increase database security
- To reduce database size
The primary goal of clustering in database management is to group similar data together. By organizing similar data into clusters, it becomes easier to retrieve relevant information and perform data analysis tasks. Clustering can also improve query performance and data organization in the database.
How does SQL handle data manipulation compared to UML?
- SQL focuses on the structure of classes and objects
- SQL is specific to NoSQL databases
- UML is a visual representation language, whereas SQL is text-based for database manipulation
- UML is more efficient in handling complex queries
SQL and UML serve different purposes in data modeling. SQL is a text-based language primarily used for querying and manipulating databases, while UML is a visual modeling language. SQL focuses on the specifics of database operations, whereas UML provides a broader visual representation of system structure and behavior.
Scenario: A library system manages books and borrowers. Each book can be borrowed by multiple borrowers, and each borrower can borrow multiple books. What type of relationship does this scenario represent, and what are its cardinality and modality?
- Many-to-Many, Mandatory
- Many-to-Many, Optional
- One-to-Many, Mandatory
- One-to-One, Optional
This scenario represents a Many-to-Many relationship with optional modality. Each book can be borrowed by multiple borrowers (Many), and each borrower can borrow multiple books (Many). The modality is optional because borrowers may not necessarily borrow books, and books may not necessarily be borrowed by borrowers.
What is the purpose of branching in version control systems for data modeling?
- Archiving old data models
- Creating backups
- Generating reports
- Managing concurrent development
The purpose of branching in version control for data modeling is to manage concurrent development. Branches allow data modelers to work on separate features or changes without affecting the main development line. This helps in organizing and merging changes efficiently.