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Dimensional Modeling 2
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Dimensional Modeling 2
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Lecture 3_ Kimball Lifecycle and Dimensional Modelling_DWM.pptx_removed.pdf Flashcards
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Question
What is Dimensional Data Modeling?
Answer
Dimensional data modeling is an analytical approach used in databases and data warehouses for organizing and categorizing facts into dimension tables.
Question
What are Dimension Tables?
Answer
Dimension tables serve as the primary source of query constraints, groupings, and report labels in a data warehouse.
Question
How are attributes used in queries or reports?
Answer
In a query or report request, attributes are identified as the by words. For example, when a user wants to see dollar sales by brand, brand must be available as a dimension attribute.
Question
What is the relationship between the quality of dimension attributes and the analytic power of a data warehouse?
Answer
The analytic power of the DWBI environment is directly proportional to the quality and depth of the dimension attributes.
Question
What is the benefit of providing dimension attributes with verbose business terminology?
Answer
The more time spent providing attributes with verbose business terminology, the better the data warehouse's effectiveness.
Question
What are surrogate keys in dimension tables?
Answer
Surrogate keys are artificial keys used instead of natural keys (e.g., Product ID) to uniquely identify rows and maintain data consistency, especially when integrating data from multiple sources.
Question
What is the difference between natural and surrogate keys?
Answer
Natural keys are based on natural data attributes, while surrogate keys are artificially created.
Question
Which type of key is more stable: surrogate key or primary key based on natural data attributes?
Answer
Surrogate keys are more stable as they do not change, while primary keys based on natural data may change if the data changes.
Question
What does a Star Schema represent?
Answer
A star schema represents each business process by a dimensional model that consists of a fact table surrounded by dimension tables, forming a starlike structure.
Question
What are the advantages of the simplicity of the dimensional schema?
Answer
The simplicity benefits business users because the data is easier to understand and navigate, and database optimizers process these simple schemas with fewer joins more efficiently.
Question
What is a Snowflake Schema?
Answer
A snowflake schema is a more normalized version of the star schema, where dimension tables are structured in multiple related tables, resembling a snowflake.
Question
What is the trade-off of using a Snowflake Schema?
Answer
While a snowflake schema reduces data redundancy, it can complicate querying because it involves more joins.
Question
How does the predictable framework of a dimensional model withstand changes?
Answer
The predictable framework of a dimensional model withstands unexpected changes in user behavior.
