Aggregations for performance in Power BI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of using aggregations in Power BI?

Aggregations help speed up report performance by summarizing detailed data into smaller, faster-to-query tables.

beginner

How do aggregations improve query speed in Power BI?

They reduce the amount of data scanned by using pre-calculated summaries instead of detailed rows.

beginner

What is an example of an aggregation you might create for sales data?

A table that sums total sales by month and region instead of listing every single sale.

beginner

True or False: Aggregations always replace detailed data in Power BI models.

False. Aggregations supplement detailed data and are used only when queries can be answered by the summary tables.

intermediate

What is a key step to enable Power BI to use aggregation tables automatically?

You must define aggregation mappings in the model so Power BI knows which summaries to use for which queries.

What does an aggregation table typically contain?

A Detailed transaction-level data

B Unrelated metadata

C Summarized data like totals or averages

D Raw data from external sources

Aggregation tables store summarized data such as totals or averages to speed up queries.

Which of these is a benefit of using aggregations in Power BI?

A Faster query response

B More complex DAX formulas

C Slower report refresh times

D Increased data storage needs

Aggregations improve performance by making queries faster.

When does Power BI use aggregation tables automatically?

A When the query matches the aggregation mapping

B Only when the user clicks a button

C Never, aggregations must be manually selected

D Only during data refresh

Power BI uses aggregation tables automatically if the query can be answered by the aggregation mapping.

Which of these is NOT a good candidate for aggregation?

A Total sales by month

B Individual transaction details

C Average customer rating by product

D Count of orders by region

Individual transaction details are detailed data, not summaries, so they are not aggregated.

What must you do before Power BI can use aggregation tables?

A Write complex SQL queries

B Delete detailed data tables

C Disable DirectQuery mode

D Create aggregation mappings in the model

Aggregation mappings tell Power BI how to use summary tables for queries.

Explain how aggregations help improve report performance in Power BI.

Think about how smaller summary tables affect query speed.

Describe the steps to set up aggregations in a Power BI model.

Focus on what you build and configure in the model.