Analyzing Data with Power BI and Power Pivot for Excel, First Edition

Chapter 6. Using snapshots

A snapshot is a kind of table that is often used in the modeling of data. In the first chapters of this book, you became familiar with the idea of dividing a model by fact tables and dimensions, and you learned that a fact is a type of event—that is, something that happens. Then, you aggregated values from the fact table by using an aggregation function, like SUM, COUNT or DISTINCTCOUNT. But the truth is, sometimes a fact is not an event. Sometimes, a fact stores something that has been measured, like the temperature of an engine, the daily average number of customers who entered a store each month, or the quantity on-hand of a product. In all these cases, you store a measurement at a point in time instead of the measure ...