Will creating too many calculate tables slow down my power bi report and is this bad practice

[akhaliq7]

I have gotten into creating calculatetables lately for my main visualization as I like the ease of using the tables as they are filtered down or the number of columns are only those that you need. Whereas not a big fan of the filter pane. Am I going down the wrong track will this slow down my report and is this bad practice, 

Just an extra question should I create relationships in the model view between dim tables and calculate tables, at time I don't need to join the specified tables together

[some_bih · Accepted solution]

Hi @akhaliq7 My experience: I use calculatedtable just in case "measure amount" is not availabe in my import table. Second "best" option: Transformation in PQ if possible comparing to calculated table. 

I usually do not do connect calculate table and dim table - I try to do overall modeling as much as possible. Relationship should be created depending on your reques. 

[AjithPrasath · Accepted solution]

Hi @akhaliq7 

Creating too many calculated tables in Power BI can potentially slow down your report's performance and is generally considered a bad practice. Here's why:

1. Increased Memory Usage: Each calculated table requires memory resources to store the calculated data. When you have a large number of calculated tables, it can consume significant memory, impacting the overall performance of your Power BI report.

2. Query Performance: Calculated tables are processed during the data refresh or query execution. When you have multiple calculated tables, each with their calculations and relationships, it can increase the query complexity and execution time. This can lead to slower query performance, especially when dealing with large datasets.

3. Maintainability and Complexity: Having numerous calculated tables can make your Power BI model more complex and harder to manage. It can become challenging to track and update calculations, especially if changes are required across multiple calculated tables.

To improve performance and maintain best practices, consider the following approaches:

1. Use Calculated Columns and Measures: Whenever possible, prefer using calculated columns or measures instead of creating additional calculated tables. Calculated columns and measures are evaluated during query execution and do not consume extra memory.

2. Optimize Calculations: Review your calculated tables and identify opportunities to optimize calculations. Look for ways to simplify or consolidate calculations. You can leverage DAX functions and techniques to improve efficiency.

3. Evaluate Query Folding: Ensure that your calculated tables support query folding. Query folding is the process by which Power BI pushes as much of the calculation and filtering work to the data source (such as SQL Server) instead of retrieving all data and performing calculations locally. This can significantly improve query performance.

4. Proper Data Modeling: Focus on creating a well-structured and efficient data model in Power BI. Design your relationships, hierarchies, and table structures thoughtfully to optimize performance. This includes using appropriate data types, minimizing unnecessary columns, and eliminating circular dependencies.

5. Regular Testing and Performance Monitoring: Test your Power BI reports and measure the performance impact of calculated tables. Monitor query response times, memory usage, and overall report performance to identify bottlenecks and areas for improvement.

For second question====> In Power BI, it is generally not necessary to create relationships between dimension tables and calculated tables if you don't need to join them together.

Best Regards,

Ajith Prasath

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[pacifist]

CalculatedColumns do not increase the memory?!

Why You Should Avoid Calculated Columns in Power BI — ehansalytics

[some_bih · Accepted solution]

Hi @akhaliq7 My experience: I use calculatedtable just in case "measure amount" is not availabe in my import table. Second "best" option: Transformation in PQ if possible comparing to calculated table. 

I usually do not do connect calculate table and dim table - I try to do overall modeling as much as possible. Relationship should be created depending on your reques.