How does data partitioning affect the scalability and fault tolerance of a distributed system?

  • Fault tolerance is not affected by data partitioning
  • Improved fault tolerance through isolation of failures
  • Improved scalability by reducing contention
  • Reduced scalability due to increased communication overhead
Data partitioning can improve scalability by reducing contention, allowing for parallel processing. Additionally, it can enhance fault tolerance by isolating failures to specific partitions, preventing system-wide failures. Understanding these effects is crucial for designing robust distributed systems.

In UML, an _______ represents an instance of a class.

  • Association
  • Attribute
  • Method
  • Object
In UML, an object represents an instance of a class. A class is a blueprint for objects, and instances of a class are created as objects. Objects encapsulate data and behavior defined by the class, providing a way to represent real-world entities in a system.

_______ is a technique used to combine multiple rows of data into a single row.

  • Aggregate
  • Join
  • Pivot
  • Unpivot
The technique used to combine multiple rows of data into a single row is called aggregation. This often involves using aggregate functions like SUM, AVG, COUNT, etc., to consolidate data and provide a more concise representation of information.

A _______ relationship is one where an entity can be related to itself through a recursive association.

  • Hierarchical
  • Many-to-Many
  • Recursive
  • Unary
A recursive relationship is one where an entity can be related to itself through a recursive association. This type of relationship is common in scenarios where an entity has a hierarchical or tree-like structure.

_______ databases are designed to scale horizontally, making them suitable for applications with high scalability requirements.

  • Graph
  • Hierarchical
  • NoSQL
  • Relational
NoSQL databases are specifically designed to scale horizontally, allowing them to handle increased loads by adding more servers to the database system. This makes them well-suited for applications with high scalability requirements, such as those experiencing rapid growth in data volume and user traffic.

In a column-family store, each column can have its own _______.

  • Data type
  • Index
  • Timestamp
  • Unique identifier
In a column-family store, each column can have its own data type. Unlike traditional relational databases, column-family stores allow flexibility in the data types within a column, providing versatility in handling various types of information efficiently.

Which normalization form ensures that every determinant in a relation is a candidate key?

  • Boyce-Codd Normal Form (BCNF)
  • First Normal Form (1NF)
  • Second Normal Form (2NF)
  • Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF) ensures that every determinant in a relation is a candidate key. This form goes beyond 3NF and addresses certain types of dependencies, making the database more robust and minimizing redundancy.

What are some potential drawbacks of denormalization?

  • Improved data integrity
  • Increased data redundancy
  • Reduced storage space
  • Simplified data maintenance
One of the potential drawbacks of denormalization is increased data redundancy. While it can enhance read performance, it comes at the cost of redundant data, which can lead to higher storage requirements and potential data inconsistency.

What are the potential drawbacks of using indexes in a database?

  • Improved query performance
  • Increased storage space and maintenance overhead
  • Reduced data redundancy
  • Simplified data retrieval process
While indexes enhance query performance, they come with drawbacks like increased storage space and maintenance overhead. Additional storage is required for index structures, and regular maintenance is needed to keep them optimized.

What benefits does version control provide in data modeling?

  • All of the above
  • Enhanced tracking of changes
  • Improved collaboration
  • Rollback to previous versions
Version control in data modeling offers various benefits, including improved collaboration, enhanced tracking of changes, and the ability to rollback to previous versions. This ensures a systematic approach to managing and evolving data models.

How does the concept of slowly changing dimensions (SCD) relate to fact tables?

  • SCD is a technique used to update fact tables in real-time
  • SCD is irrelevant in the context of fact tables
  • SCD is only applicable to dimension tables, not fact tables
  • SCD is used to handle changes in dimension attributes over time, impacting both dimension and fact tables
Slowly Changing Dimensions (SCD) are used to manage changes in dimension attributes over time. This is crucial in data warehousing for historical analysis. When changes occur in dimensions, it affects related fact tables as well. Understanding this relationship is vital for designing accurate and comprehensive data warehouses.

How does a UNIQUE constraint contribute to maintaining data integrity?

  • Allows NULL values in columns, ensuring flexibility
  • Ensures that all rows in a table have a unique combination of values in specified columns
  • Forces each row in a table to have a different primary key value
  • Validates that foreign key values exist in the referenced table
A UNIQUE constraint ensures that all rows in a table have a unique combination of values in the specified columns. This helps maintain data integrity by preventing duplicate records, ensuring that each row is distinct based on the defined uniqueness criteria.