Hi @Anonymous ,
Most data sources that have the concept of a query language support query folding. These data sources can include relational databases, OData feeds (including SharePoint lists), Exchange, and Active Directory. However, data sources like flat files, blobs, and web typically do not.
In the Power Query Editor window, it's possible to determine when a Power Query query can be folded. In the Query Settings pane, when you right-click the last applied step, if the View Native Query option is enabled (not greyed out), then the entire query can be folded.
If the View Native Query option isn't enabled (greyed out), this is evidence that not all query steps can 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 so, then you've learned where, in the sequence of steps, that query folding could no longer be achieved.
More details: Power Query query folding
In most cases, Power BI Desktop attempts to perform this verification for you when defining the incremental refresh policy. For SQL based data sources such as SQL Database, Azure Synapse, Oracle, and Teradata, this verification is reliable. However, other data sources may be unable to verify without tracing the queries. If Power BI Desktop is unable to confirm, a warning is shown in the Incremental refresh policy configuration dialog.
If you see this warning and want to verify the necessary query folding is occurring, use the Power Query Diagnostics feature or trace queries by using a tool supported by the data source, like SQL Profiler. If query folding is not occurring, verify the filter logic is included in the query being passed to the data source. If not, it's likely the query includes a transformation that prevents folding.
Before configuring your incremental refresh solution, be sure to thoroughly read and understand Query folding guidance in Power BI Desktop and Power Query query folding. These articles can help you determine if your data source and queries support query folding.
If I have misunderstood your meaning, please provide more details.
Best Regards
Community Support Team _ Polly
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