We have a Tabular model on Azure Analysis Services and we are using the Azure Data Gateway to read from our EDW. As an example, our Fact table is about 100MB using columnstore compression. Uncompressed, it is about 4GB.
My question is, when we process the Tabular model on Azure, does 100MB or 4GB of data go through the gateway up to Azure Analysis Services?
(And similarly if it was page compression, would it shift the compressed data through the gateway or uncompressed?)
when we process the Tabular model on Azure, does 100MB or 4GB of data go through the gateway up to Azure Analysis Services?
When the data is sent from SQL Server to the gateway (or any client) it is always uncompressed. The network protocol for SQL Server only supports uncompressed data.
The gateway encrypts and compresses all the data it sends, but you'll have to monitor it directly to see how much data is being sent during the refresh. See eg https://learn.microsoft.com/en-us/power-bi/service-gateway-performance-monitoring