What common mistakes lead to slow report loading times and how do you fix inefficient M code or DAX queries

0 votes
What common mistakes lead to slow report loading times, and how do you fix inefficient M code or DAX queries?

I'm working on a Power BI report with large datasets, and it’s loading very slowly. I suspect that inefficient M code and DAX queries are causing the delays, but I’m not sure which specific practices or coding structures might be responsible. What common mistakes can lead to slow loading times in Power BI, and what steps can I take to optimize or refactor inefficient M code and DAX queries?
Nov 4 in Power BI by Evanjalin
• 7,890 points
63 views

1 answer to this question.

0 votes

They include inefficient M code in the Power Query and DAX queries that are not optimized. Here are some of the common mistakes and solutions to help mitigate them.

Eliminating Unneeded Steps and Columns: In Power Query, each transformation step increases the time taken by the processing engine. The performance can also be significantly improved by eliminating unnecessary processes and steps, aggressive filtering of rows after early stages, and vertical reduction of columns to the bare minimum needed for analysis. Loading only required data minimizes memory consumption, therefore ensuring quick processing. In the same vein, do not bring in entire tables when only certain columns or rows are of interest - this simplifies the query and improves the speed of the report.

DAX Calculation Optimization: One key area that may affect speed is the quality of the DAX queries used. One frequent error is when performing ‘row by row’ calculations by means of functions such as FILTER or CALCULATE, which work on voluminous tables. Instead, use aggregate data in its source when practicable. However, measures should refrain from applying functions that have the variable attribute, such as NOW and TODAY, as they tend to recalculate every time there’s a change. It is also possible to use variables (VAR) in DAX on different calculations that occur within the same measure and utilize the stored value instead of recalculation, leading to less processing time.

Diminishing Complexity of Data Models: Complex data models, especially those that are heavily interlinked with many two-way relationships, risk compromising the performance of reports. The performance of the data model structure may be enhanced by eliminating redundant tables or utilizing one-directional relationships where possible. Furthermore, creating and utilizing summary tables for data with high cardinality, like transactional data for visual aids made up of these tables, can also ease the processing unit for such reports, hence reducing the time taken to load the reports.

Optimizing the steps in Power Query, DAX logic, and the data model itself can improve report performance and provide users with a more comfortable experience.

answered Nov 4 by pooja
• 8,470 points

Related Questions In Power BI

0 votes
0 answers
0 votes
0 answers
0 votes
0 answers
0 votes
0 answers
0 votes
1 answer

How to export Power Queries from One Workbook to Another with VBA?

Try solving it using the Workbook. Query ...READ MORE

answered Oct 22, 2018 in Power BI by Annie97
• 2,160 points
6,789 views
0 votes
1 answer

Excel Power Query: Using List.MatchAny on a column value

try this. let TableA = ...READ MORE

answered Oct 22, 2018 in Power BI by Annie97
• 2,160 points
4,287 views
0 votes
1 answer

How can I search for multiple strings?

A simple solution is this: List.ContainsAny(Text.SplitAny("This is a test ...READ MORE

answered Oct 24, 2018 in Power BI by Upasana
• 160 points
4,731 views
0 votes
1 answer

Power Query Web request results in “CR must be followed by LF” Error

What I think is, it might look ...READ MORE

answered Oct 29, 2018 in Power BI by Shubham
• 13,490 points
1,903 views
+1 vote
1 answer

How do you fix incorrect totals or results caused by filter context issues in DAX?

In order to address calculation errors or ...READ MORE

answered Oct 29 in Power BI by pooja
• 8,470 points
119 views
0 votes
1 answer

What strategies do you use for writing efficient DAX code to handle large fact tables with millions of rows?

In Data Analytics eXpressions (DAX), when dealing ...READ MORE

answered Oct 29 in Power BI by pooja
• 8,470 points
202 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP