The real purpose of choosing SSAS tabular model for power bi

[Anonymous]

Can someone please help me to understand the reason to go for ssas tabular model for power bi, other than Self service BI. 

[v-qiuyu-msft]

Hi @Anonymous ,

Not sure I got your point. Do you mean is designing data model in SSAS tabular then connect to the tabular live in Power BI desktop, or designing data model in Power BI desktop directly better? 

There are many difference in these two ways. When connecting live to the SSAS tabular in Power BI desktop, all the modeling functions are not working(define relationship, change column data type, ..etc), we can just create report level measures. Each time you want to edit data model, you need to do it on SSAS side. If SSAS tabular model is used by many users and the model needn't to change frequently, you can try this way. Otherwise, I would suggest you connect to the data source directly and design data model in Power BI desktop, all the modeling function can be finished in Power BI desktop by report author, needn't to contact the SSAS admin to design or modify the model. 

Best Regards,
Qiuyun Yu 

[Anonymous]

Hi Qiuyun Yu,

Thanks for your response.

I could understand the technical difference between SSAS tabular in power bi VS Direct Query/Import Data into power bi. I need to understand the necessity of SSAS/AAS as semantic layer, for power bi, in terms of processing power, performance and data limits. If there is no advantage of using SSAS/AAS to improve the processing power/performance, then I don't need to go for SSAS.

Please advise.

[v-qiuyu-msft]

Hi @Anonymous ,

The Power BI has a internal SSAS instance to processing data. You can refer to this article: https://www.microsoftpressstore.com/articles/article.aspx?p=2449192. 

In Power BI, to optimize the report, we can follow this document: https://docs.microsoft.com/en-us/power-bi/power-bi-reports-performance

Best Regards,
Qiuyun Yu