AWS Redshift string column type and Direct Query i PowerBI desktop

[Krystian_overga]

Direct queries that include columns with string type with an AWS Redshift source do not work. It works when in import mode. What is going on? The error message is "

Error fetching data for this visual

OLE DB or ODBC error: [Expression.Error] We couldn't fold the expression to the data source. Please try a
simpler expression ..

"

[Krystian_overga · Accepted solution]

There are no transformations involved. 

When I change the data type i Redshift from string to varchar(x) then it works.

[uzuntasgokberk]

Hello @Krystian_overga ,

Could you please share your applied steps for redshift data in Transform data. I can give more correct comments. However, I assume that you applied steps that some of them doesn't fold for example replace error, remove duplicate cannot fold. Whenever, you use the steps that cannot support query folding, Power bı wants to switch direct query storege mode to import mode.
More information about query folding:
https://learn.microsoft.com/en-us/power-query/query-folding-basics
https://medium.com/microsoft-power-bi/boosting-power-bi-performance-with-query-folding-techniques-75...

Kind Regards,
Gökberk Uzuntaş

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