How does database normalization contribute to data integrity?

  • Adding redundancy to ensure data availability
  • Improving query performance
  • Increasing the size of the database
  • Reducing redundancy and dependency among data
Database normalization contributes to data integrity by reducing redundancy and dependency among data. By organizing data into tables and eliminating data duplication, normalization minimizes the chances of inconsistencies and update anomalies. It ensures that data is stored logically and efficiently, promoting accuracy and reliability.

Scenario: A retail company wants to analyze sales data, including sales volume, revenue, and product categories. Which schema would you recommend for their data warehouse: Star Schema or Snowflake Schema, and why?

  • Snowflake Schema, because it allows for easier data maintenance and scalability.
  • Snowflake Schema, because it supports more complex relationships and enables better data normalization.
  • Star Schema, because it facilitates efficient query performance and is easier to implement.
  • Star Schema, because it simplifies queries and is more suitable for denormalized data structures.
For a retail company analyzing sales data, a Star Schema would be more appropriate. Star Schema denormalizes data, simplifying queries and enhancing performance, crucial for analytical tasks common in sales analysis. Its structure with a central fact table surrounded by dimension tables suits the needs of reporting and analysis in retail sales, where querying across different dimensions like time, product, and geography is essential.

What is a key-value store in NoSQL database systems?

  • A data store limited to string values only
  • A database system that exclusively uses foreign keys
  • A database system that stores data in a flexible, schema-less way using key-value pairs
  • A system that uses only numeric keys for data retrieval
In a NoSQL key-value store, data is stored as key-value pairs, where the key is a unique identifier and the value is the associated data. This model allows for efficient and fast retrieval of data, making it suitable for various applications like caching and session storage.

How does query optimization contribute to database performance tuning?

  • By improving the security of the database
  • By increasing the complexity of SQL queries
  • By increasing the storage space of the database
  • By reducing the execution time of SQL queries
Query optimization involves improving the efficiency of SQL queries, which in turn reduces the execution time. This is achieved through various techniques such as index optimization, query rewriting, and statistics collection, all aimed at enhancing the performance of database operations.

What is the difference between aggregation and summarization in data modeling?

  • Aggregation and summarization are interchangeable terms with no distinct difference.
  • Aggregation combines detailed data into a higher-level view, while summarization involves creating a concise summary of data.
  • Aggregation is used for numeric calculations, while summarization is for textual data.
  • Aggregation only works with relational databases, while summarization is more versatile.
In data modeling, aggregation involves the grouping of detailed data into a higher-level view, often using functions like COUNT, AVG, etc. Summarization, on the other hand, is the process of creating a concise summary of data, providing a more comprehensive overview. Understanding this difference is crucial for effective data modeling and reporting.

In an ERD, what does a cardinality of "One-to-One" signify?

  • Each entity in the first table can be related to at most one entity in the second table
  • Each entity in the first table can be related to multiple entities in the second table
  • Each entity in the first table can be related to only one entity in the second table
  • Each entity in the first table can be related to only one entity in the second table, and vice versa
A cardinality of "One-to-One" in an ERD signifies that each entity in the first table can be related to only one entity in the second table, and vice versa. This type of relationship is less common but is useful in certain scenarios where a strict one-to-one association is needed.

_______ compression algorithms utilize statistical methods to represent data more efficiently.

  • Adaptive
  • Entropy
  • Lossy
  • Predictive
Entropy compression algorithms utilize statistical methods to represent data more efficiently. These algorithms analyze the frequency of symbols in the data and assign shorter codes to more frequent symbols, resulting in overall compression.

Graph databases provide native support for _______ operations, allowing efficient querying of connected data.

  • Aggregation
  • Indexing
  • Sorting
  • Traversal
Graph databases provide native support for traversal operations, allowing efficient querying of connected data. Traversal involves navigating through nodes and relationships in a graph to discover patterns or retrieve specific information, which is a key feature in graph databases.

A degenerate dimension in a fact table does not have a corresponding _______ table.

  • Dimension
  • Lookup
  • Master
  • Reference
A degenerate dimension in a fact table does not have a corresponding dimension table. Instead, the dimension attributes are stored directly in the fact table. This is suitable when the dimension has no significant details other than its key and is not reused across multiple facts.

The integration of ER diagram tools with _______ enhances data modeling efficiency.

  • Cloud Services
  • Code Editors
  • Database Management Systems
  • Project Management Tools
Integrating ER diagram tools with Database Management Systems (DBMS) enhances data modeling efficiency. This integration allows for a direct connection between the ERD and the underlying database, facilitating synchronization and real-time updates between the data model and the actual database structure.