Choose a Power BI model framework

Question 1

What is a Power BI data model?

Answer 1

A query-able data resource optimized for analytics, used in Power BI for creating reports and dashboards.

Question 2

What is a Power BI dataset?

Answer 2

A Power BI artifact published to a workspace in the Power BI service, used as a source of data for visualizations.

Question 3

What are the three phases of an analytic query?

Answer 3

Filter, group, and summarize.

Question 4

What is a tabular model in Power BI?

Answer 4

A model comprising tables of columns, relationships, hierarchies, and calculations.

Question 5

What is the star schema design?

Answer 5

A modeling approach that classifies tables as either dimension or fact, optimizing for analytics and ease of use.

Question 6

What are the table storage modes in Power BI?

Answer 6

Import, DirectQuery, and Dual.

Question 7

What determines the model framework in Power BI?

Answer 7

The table storage mode settings, leading to import, DirectQuery, or composite models.

Question 8

What is an import model in Power BI?

Answer 8

A model with tables set to Import storage mode, including calculated tables defined with DAX formulas.

Question 9

What are the benefits of import models?

Answer 9

They support all Power BI data source types, DAX and Power Query functionality, calculated tables, and deliver the best query performance due to in-memory storage optimization.

Question 10

What are the size limitations of import models in Power BI?

Answer 10

Shared capacity models have a 1-GB limit per dataset, while dedicated capacity models can exceed 10-GB with the Large dataset storage format setting enabled.

Question 11

What strategies can reduce the size of data in import models?

Answer 11

Removing unnecessary columns and rows, summarizing data, optimizing column data types, and using DirectQuery for specific tables.

Question 12

How does data refresh work in import models?

Answer 12

Data must be periodically refreshed, with up to eight times per day in shared capacity and up to 48 times per day in dedicated capacity, depending on data velocity and urgency.

Question 13

What is incremental refresh in Power BI?

Answer 13

A feature that automates time-period partition creation and management, updating only necessary partitions to reduce the burden on source systems and improve refresh performance.

Question 14

What is a DirectQuery model in Power BI?

Answer 14

A model where tables have their storage mode set to DirectQuery, allowing real-time query results by querying the underlying data source directly.

Question 15

When should you use a DirectQuery model?

Answer 15

When dealing with large or fast-changing data sources, enforcing source row-level security (RLS), adhering to data sovereignty restrictions, or creating specialized datasets.

Question 16

What are the benefits of DirectQuery models?

Answer 16

They support large data volumes, enable near real-time data updates, enforce source RLS, and comply with data sovereignty restrictions.

Question 17

What are the limitations of DirectQuery models?

Answer 17

Not all data sources are supported, limited Power Query transformations, potential slow query performance, and possible impact on source system performance.

Question 18

How can you boost the performance of DirectQuery models?

Answer 18

Optimize the source database with indexes and materialized views, and use user-defined aggregation tables to handle higher-grain analytic queries.

Question 19

What is a composite model in Power BI?

Answer 19

A model that combines more than one source group, typically including both Import and DirectQuery storage modes.

Question 20

What are the benefits of using a composite model in Power BI?

Answer 20

Design flexibility, performance boosts by caching data, and the ability to extend models with new calculated columns and tables.

Question 21

What is a limitation of composite models regarding data refresh?

Answer 21

Imported data may become out of sync with DirectQuery data, requiring periodic refreshes to maintain consistency.

Question 22

How can DirectQuery model performance be improved using composite models?

Answer 22

By adding import aggregation tables and using dual storage mode for dimension tables.

Question 23

What is a dual storage mode table?

Answer 23

A table that can use both import and DirectQuery storage modes, with Power BI selecting the most efficient mode at query time.

Question 24

How does the real-time data option work with incremental refresh in composite models?

Answer 24

It creates a hybrid table with import partitions for older data and a DirectQuery partition for current data, enabling real-time updates.

Question 25

When should you choose the import model framework in Power BI?

Answer 25

Whenever possible, as it offers the most options, design flexibility, and fast performance, with data reduction techniques to load the least amount of data.

Question 26

When is the DirectQuery model framework most appropriate?

Answer 26

When your data source stores large volumes of data and your report needs to deliver near real-time data.

Question 27

What are the benefits of a composite model framework?

Answer 27

It boosts the query performance of DirectQuery models, delivers near real-time query results from import models, and extends Power BI datasets with additional data.

Question 28

How can you improve DirectQuery model performance in a composite model?

Answer 28

By using import aggregation tables and setting related dimension tables to dual storage mode for higher-grain query satisfaction from cache.

Question 29

What is a hybrid table in a composite model?

Answer 29

A table with import partitions for older data and a DirectQuery partition for the current period, providing near real-time query results.

Question 30

What should be considered when planning model frameworks in Power BI?

Answer 30

It’s possible to convert a DirectQuery table to an import table in Power BI Desktop, but not vice versa.