When might denormalization be beneficial in database design?
- To enforce data integrity constraints
- To improve read performance in a data warehouse
- To reduce redundancy and storage space
- To simplify complex queries
Denormalization can be beneficial in database design when there is a need to improve read performance in a data warehouse scenario. It involves strategically introducing redundancy to streamline query processing and retrieval of large datasets.
What is the primary goal of Reverse Engineering in database management?
- To create a conceptual data model
- To create a physical data model
- To generate a higher-level model from an existing database schema
- To optimize database performance
Reverse Engineering in database management aims to generate a higher-level model, such as a conceptual data model, from an existing database schema. This process is useful for understanding and documenting an already implemented database structure.
_______ is a constraint that enforces data integrity by ensuring that a column cannot contain NULL values.
- Foreign Key
- NOT NULL
- Primary Key
- Unique Key
NOT NULL is a constraint that enforces data integrity by ensuring that a column cannot contain NULL values. It is used to specify that a column must have a value, preventing the insertion of records with missing or undefined data.
Column-family stores are optimized for _______ and _______.
- Consistency, Availability
- Read-intensive workloads, Write-intensive workloads
- Readability, Writeability
- Transactions, Indexing
Column-family stores are optimized for both read-intensive and write-intensive workloads. This makes them suitable for scenarios where there is a need for high scalability and performance in both read and write operations.
The _______ model in NoSQL databases allows nested structures and dynamic schemas.
- Column-Family
- Document
- Graph
- Key-Value
The Document model in NoSQL databases allows nested structures and dynamic schemas. This means that each document in the database collection can have a different structure, allowing for flexibility in data representation.
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.
_______ 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.
_______ 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.
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.
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.