Data partitioning can lead to _______ as data access may involve multiple partitions.
- Latency
- Overhead
- Parallelism
- Redundancy
Data partitioning can lead to increased latency as data access may involve multiple partitions. Coordinating the retrieval of data from different partitions introduces additional time, and careful consideration is needed to mitigate latency in distributed environments.
In SQL, the HAVING clause is used to apply conditions to groups created by the _______ clause.
- GROUP BY
- ORDER BY
- SELECT
- WHERE
In SQL, the HAVING clause is used to apply conditions to groups created by the GROUP BY clause. This allows you to filter the results of aggregate functions based on specified criteria, providing more flexibility in analyzing grouped data. It is commonly used in conjunction with GROUP BY to filter aggregated results.
A _______ schema in Dimensional Modeling organizes data into facts and dimensions for optimized querying.
- Entity
- Fact
- Snowflake
- Star
In Dimensional Modeling, a Star Schema organizes data into a central fact table surrounded by dimension tables. The fact table contains quantitative data, and dimension tables provide context to the data. This schema design simplifies queries, improves performance, and is commonly used in data warehousing for analytical purposes.
In the context of data warehousing, what is the significance of degenerate dimensions in a fact table?
- A degenerate dimension is a dimension that is also used as a measure in the fact table
- A degenerate dimension is an alternative term for a primary key
- A degenerate dimension is derived from other dimensions
- A degenerate dimension is irrelevant in data warehousing
In data warehousing, a degenerate dimension is a dimension key that does not have its own dimension table but is instead stored in the fact table. It's essentially a dimension attribute that is treated as a measure due to its significance in analysis. Understanding this is crucial for designing efficient data warehouses.
How does Dimensional Modeling contribute to data warehouse performance?
- All of the above
- By providing efficient aggregations
- By reducing data redundancy
- By simplifying complex queries
Dimensional Modeling contributes to data warehouse performance by reducing data redundancy, simplifying complex queries, and providing efficient aggregations. This design approach optimizes query performance and facilitates faster data retrieval, which is crucial for data warehouse efficiency.
In a fact table, surrogate keys are used instead of _______ keys to uniquely identify each record.
- Composite
- Foreign
- Natural
- Primary
In a fact table, surrogate keys are used instead of natural keys to uniquely identify each record. Surrogate keys are system-generated and provide a stable identifier, avoiding the complexities that can arise with changes in natural keys. This enhances the stability and efficiency of the data warehouse.
The process of loading data into a Data Warehouse or Data Mart is known as _______.
- ETL (Extract, Transform, Load)
- Extraction
- Loading
- Transformation
The process of loading data into a Data Warehouse or Data Mart is known as ETL (Extract, Transform, Load). This involves extracting data from source systems, transforming it into a suitable format, and loading it into the target data repository for analysis and reporting.
The _______ constraint ensures that a column does not contain NULL values.
- CHECK
- DEFAULT
- NOT NULL
- UNIQUE
The NOT NULL constraint ensures that a column does not contain NULL values. It is used to enforce data integrity by requiring each value in the specified column to be filled with valid data.
What are the key differences between a superclass and a subtype in a Generalization and Specialization hierarchy?
- Subtypes and superclasses cannot have relationships
- Subtypes inherit attributes from the superclass, but may have additional attributes
- Superclass inherits attributes from subtypes
- Superclass is always a disjoint entity
In a Generalization and Specialization hierarchy, subtypes inherit attributes from the superclass but may have additional attributes specific to their category. This allows for a more detailed representation of data within the model.
In database design, what is the process of Reverse Engineering commonly used for?
- Creating a conceptual model
- Generating a database schema from existing code or structures
- Modifying data in the database
- Normalizing data tables
Reverse Engineering in database design is commonly used for generating a database schema from existing code or structures. It involves analyzing an existing database or software to understand its structure and then creating a visual representation of that structure, such as an Entity-Relationship Diagram (ERD).
Aggregation functions like SUM, AVG, MIN, and MAX operate on a set of _______.
- Columns
- Rows
- Tables
- Values
Aggregation functions like SUM, AVG, MIN, and MAX operate on a set of values. These functions perform calculations on a column of data to produce a single result, such as the sum or average of the values in that column. Understanding how to use aggregation functions is crucial for data analysis and reporting.
Scenario: A company has a database table with attributes {EmployeeID, EmployeeName, DepartmentName, DepartmentLocation}. Is this table in the Boyce-Codd Normal Form (BCNF)?
- Cannot be determined
- No
- Not applicable
- Yes
No