Working of SSAS Multidimensional With Live Connection in Power BI

[bhavesh-jadav]

Hello there,

I am using live connection to SSAS Multidimensional cube. There are performance issues while loading data in visuals in Power BI so we got the trace of the all the queries that ran on the cube. After looking the queries in trace, I found out that Power BI was sending complex DAX quries to Multidim cube.

We have reports in Tableau which uses same multidim cube and in trace I see that Tableau sends MDX queries rather than DAX for which duration time is less compared to DAX sent by Power BI.

My question is that does multidim cube converts DAX into MDX at the cube side or does multidim cube runs DAX as native query rather than doing conversion? If no conversation is happening than why there is perfromance gap in methods used by Power BI and Tableau when sending queries to the cube for execution?

[v-shex-msft]

Hi @bhavesh-jadav,

>>My question is that does multidim cube converts DAX into MDX at the cube side or does multidim cube runs DAX as native query rather than doing conversion?

Nope, current power bi not support to manually generate or modify queries which you mentioned.

>>If no conversation is happening than why there is perfromance gap in methods used by Power BI and Tableau when sending queries to the cube for execution?

I don't think power bi desktop can support all features which AS Multidimensional has, when you use live connection mode, it maybe handle them on AS side and pull result to power bi side to visualizations.

You can also take a look at following link about power bi performance:

Power BI Performance Best Practices

Regards,

Xiaoxin Sheng