This tutorial will talk about optimizing your queries in DAX Studio. You’ll also learn how to mitigate the presence of the CallBackDataID if ever they appear in your calculations. This will help improve DAX’s performance in generating accurate data.
If you recall from previous blog posts, CallBackDataID appears when the storage engine asks help from the formula engine to solve complex queries. This process takes time and makes DAX slower because of the presence of the formula engine.
The CallBackDataID is a good place to start your optimizations. But depending on the results you want to obtain, optimization is not always necessary.
These are the common causes for having a CallBackDataID and their mitigations.
Mitigating CallBackDataID And Optimizing DAX Queries
First is the use of Error Handling like ISERROR. A CallBackDataID may occur if you’re dividing something and a value is provided depending on the answer. To mitigate this, “catch” potential errors before the calculation begins.
Next is the use of IF and FILTER in your iterators. From the previous modules, a sample query with an IF and FILTER was shown. That query generated a CallBackDataID in the Servers Timings tab. The solution is to move the filters to a CALCULATE statement.
The use of date functions like LASTDATE may also generate a CallBackDataID. This is because of the DAX engine evolving and understanding dates. You can easily solve it by using MIN or MAX because it gives you at most the same results.
The last cause is the use of math functions like ROUND or FLOOR. These are complex expressions that the storage engine can’t handle. You have to take care of it in the ETL process in Power Query.
If you look at your Serving Timings and Query Plans tabs and see the CallBackDataID, look at the total execution time. If it takes a lot of time, you need to optimize it. Otherwise, you can just leave it and focus on finding other performance issues.
Mitigating the CallBackDataID is a matter of trial and error. If you rewrite your queries to eliminate the CallBackDataID, you may end up having a slower DAX performance because your query may increase the amount of data caches or the materialized rows. So it’s all up to you and how you format your query to get the best possible performance.
***** Related Links *****
Storage Engine In Power BI – VertiPaq Operators & Queries
Measure In Power BI: Optimization Tips And Techniques
VertiPaq Analyzer In DAX Studio | Power BI Tutorial
Conclusion
Every problem has their own solution. In the case of the CallBackDataID, it has different approaches and mitigations in order to increase DAX’s efficiency in providing results. This solutions can be used if your queries tend to take time in releasing data.
Learn and understand more about these optimization techniques by practicing them in your report. You may also read other optimization tutorials in other modules to broaden your knowledge and improve DAX performance.
Nick
