Hi @Anonymous ,
As @mwegener has said, if the data source can support Direct Query, itself can support query folding, because For a DirectQuery or Dual storage mode table, the Power Query query must achieve query folding, and the IBM Netezza can support direct query based on this document.
But we noticed you are using incremental refresh in Import Storage mode, if you make a complate query, some sub-query may not support query floding even the source can support, but there are only some transformations in power query editor can be query floded based on this documnet.
In most cases, we can use View Native Query option to determine when a Power Query query can be folded, But based on this document, 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. In additional, If the View Native Query option is not enabled (greyed out), this is evidence that all query steps cannot be folded. However, it could mean that a subset of steps can still be folded. Working backwards from the last step, you can check each step to see if the View Native Query option is enabled. If this is the case, then you have learned where, in the sequence of steps, that query folding could no longer be achieved.
At last, based on this document, If you want to check that the necessary query folding is occurring, you can use the Query Diagnostics feature, or trace queries received by the source database.
Best regards,
Community Support Team _ Dong Li
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