Be mindful of query folding and its impact on data refresh

Data modelers need to pay extra attention to query folding. Not only can query folding affect the performance of a data refresh but it can also hit resource utilization during the data refresh. Query folding is essential for the very same reason an incremental data refresh is, so if the refresh takes too long due to the queries not being folded, the incremental data refresh never happens. It is also crucial for the models in either DirectQuery or Dual storage mode as each transformation step must be folded. As query folding is a vital topic, it is good to spend some time to see what it is all about.

Understanding query folding

Query folding is simply the Power Query engine’s capability to translate the transformation steps into the native query language. Therefore, based on the Power Query engine’s capability, a query in the Power Query Editor may be fully folded or partially folded. For instance, we...