Forum Discussion
Get data into Power BI
What is the difference in terms of performance and data transfer between using a query to bring data vs bringing the entire table and do the transformation in Power Query?
To be more clear, I can bring data using this query
select FieldA, FieldB, FIeldC from Table1 where FieldB='X'
or I can bring the entire Table1 and then apply transformations in PowerQuery to get to the same final result.
Opinions?
2 Replies
I think we've found it best to get the data pared down as much as possible using sql, rather than transforming in Desktop. The database is optimized to run these statements very fast and usually has more power than your local machine. So, I would suggest letting the database server churn over your data, and then do minimal transformations in the Power BI model.
I think, writing a query to bring in the data - performance depends up on the database on which you are running the query beacuse query is executed by your backend database.
If you bring in the data and then applying tranformation - performance depends up on your RAM in your machine where you are running the power bi.
Usually, Memory operations are faster than Database operations.
Data Transfer depends on the number of rows you are pulling.
