From the Introduction
How does Power Query’s mashup engine process the expressions you write? Query folding is one key concept—where behind the scenes, the engine may transform part or all of your M code into the data source’s native query language then ask the source to execute that query. Streaming, though perhaps a less familiar term, is even more fundamental, as it describes how table, list and binary data flows between functions in M.
Let’s take the mystery out of these two terms—but before we get to them, we’ll lay a foundation of basic concepts about how the Power Query language works. Altogether, the goal of our time together is to give you an understanding of How Power Query Thinks, so you can write more efficient mashups, are better positioned to debug problems, and can avoid unexpected variability in results.
Users’ Group Presentation
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