The three major connectivity modes in Power BI are :
Direct Query : The method allows direct connection to the Power BI model. The data doesn’t get stored in Power BI. Interestingly, Power BI will only store the metadata of the data tables involved and not the actual data. The supported sources of data query are:
* Amazon Redshift
* Azure HDInsight Spark (Beta)
* Azure SQL Database
* Azure SQL Data Warehouse
* IBM Netezza (Beta)
* Impala (version 2.x)
* Oracle Database (version 12 and above)
* SAP Business Warehouse (Beta)
* SAP HANA
* Snowflake
* Spark (Beta) (version 0.9 and above)
* SQL Server
* Teradata Database
Live Connection : Live connection is analogous to the direct query method as it doesn’t store any data in Power BI either. But opposed to the direct query method, it is a direct connection to the analysis services model. Also, the supported data sources with live connection method are limited:
* SQL Server Analysis Services (SSAS) Tabular
* SQL Server Analysis Services (SSAS) Multi-Dimensional
* Power BI Service
Import Data (Scheduled Refresh) : By choosing this method, you upload the data into Power BI. Uploading data on Power BI means consuming the memory space of your Power BI desktop. If it is on the website, it consumes the space of the Power BI cloud machine. Even though it is the fastest method, the maximum size of the file to be uploaded cannot exceed 1 GB until and unless you have Power BI premium (then you have 50 GB at the expense).
But which model to choose when depends on your use and purpose.
