Merge/Join and Query Folding

[Anonymous]

Hi all

I am trying to fold a query which joins two tables

I have attempted Table.NestedJoin and Table.Join, trying both LeftOuter and Inner.

When I look at the diagnostic steps, both left and right queries are folded indepently and then handed over to the mash up evaluator. No join statemen is shown at all.

I am using the Redshift connector.

From investigations, I believed NestedJoin would not fold the "merge" section but will return to folding at "expanded column" but this is not the case. Artivles suggested to use Table.Join to create the native SQL but this did not work.

https://towardsdatascience.com/query-folding-in-power-bi-devil-is-in-the-detail-d564ab0cb32 - this site successfully used Table.Join

Is this possible through the Redshift connector?

[Anonymous]

You would think that they would post the M code for these connectors on the connector reference page...that's a problem. 

--Nate

[AlexisOlson]

Just in case you're missing something simple, are the two tables coming from the same source? (Query folding isn't possible if the two queries can't be combined into a single SQL statement evaluated at a single source.)

[Anonymous · Accepted solution]

Thanks Alexis. They were coming from the same source.

My issue was that  I changed column datatype on the table I was joining. Removing this step allowed folding to occur. I changed the datatype after that step! All fixed..!