Data Warehouse вопросы и ответы для интервью
Вопрос 11. What is a fact table in a Data Warehouse?
A fact table is a central table in a star or snowflake schema that contains quantitative data (facts) related to business processes. It is typically surrounded by dimension tables and facilitates data analysis.
Example:
In a sales data warehouse, the fact table may contain sales revenue, quantity sold, and profit margin.
Вопрос 12. Explain the concept of conformed dimensions.
Conformed dimensions are dimensions that have consistent meaning and values across different data marts or parts of a data warehouse. They provide a standardized view of data for consistent reporting and analysis.
Example:
A 'Date' dimension that is shared and consistent across multiple data marts within an organization.
Вопрос 13. What is a surrogate key in the context of Data Warehousing?
A surrogate key is a unique identifier assigned to a dimension or fact table in a data warehouse. It is used for efficient data retrieval and management, especially when natural keys may change over time.
Example:
Using a surrogate key to uniquely identify customers in a dimension table instead of using the customer's name.
Вопрос 14. What is the role of a data steward in Data Warehousing?
A data steward is responsible for managing and ensuring the quality, integrity, and security of data within a data warehouse. They play a key role in defining data standards, policies, and governance.
Example:
A data steward may define rules for data cleansing and validation to maintain high data quality in the warehouse.
Вопрос 15. Explain the concept of data partitioning in a Data Warehouse.
Data partitioning involves dividing large tables into smaller, more manageable segments based on certain criteria, such as date ranges or key values. It improves query performance and facilitates data management.
Example:
Partitioning a sales fact table based on the sales date to optimize queries that involve specific time periods.
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