Query Folding - ODBC

[mserpas]

I'm connected to an Impala database using the Cloudera ODBC connector. The Power BI documentation claims that most ODBC connections should be able to support query folding. However, every query I attempt looks like it is not folding (View NativeQuery button is greyed out in my Query Editor).

I at first was using a more complex query, but now am just attempting a simple SELECT *, and yet, the query is still not folding. 

Any tips or tricks here would be great because I'm at a complete loss for what about at SELECT * query is unfoldable. 

[v-stephen-msft · Accepted solution]

Hi @mserpas ,

1.The View Native Query option is only available for certain relational DB/SQL generating connectors. It doesn't work for OData based connectors, for example, even though there is folding occurring on the backend. The Query Diagnostics feature is the best way to see what folding has occurred for non-SQL connectors (although the steps that fold aren't explicitly called out—you just see the resulting URL that was generated).

2.Query folding supports SQL Server, Oracle, and data sources that support ODBC connectivity.

Excel, CSV, and website are not supported.( Data sources without any query mechanism).

3.If the query statement is preconfigured before connecting the data source, query folding will not work.

4.Note that when a Power Query query encompasses multiple data sources, incompatibility of data source privacy levels can prevent query folding from taking place.

Best Regards,

Stephen Tao

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

[amitchandak]

@mserpas , This cod talks about " Wrapping the Odbc.DataSource function will allow your connector to inherit default query folding behavior based on the capabilities reported by your driver."

Not sure this can really help you, but check : https://docs.microsoft.com/en-us/power-query/odbc

others:

https://docs.microsoft.com/en-us/power-query/power-query-folding

https://blog.crossjoin.co.uk/2019/01/04/odbc-power-bi-power-query-refresh-performance/