A summarised copy of a fact table at a coarser grain or with fewer dimensions (daily store sales, for instance) that makes frequent queries faster. Power BI semantic models can achieve the same result through user-defined aggregations.
Also called aggregate fact table, summary table.
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Terms in this definition
- Fact table
Stores the numbers captured when business events happen, like what each sale brought in; an analytical model rolls these up into measures and slices them by dimensions.
- Grain
What a single row in a fact table stands for at its most detailed level, defined by its dimension keys and attributes, such as one row for each order line on each day.
- Power BI
Microsoft's analytics and reporting service. It reaches data held on-premises through the on-premises data gateway.
- Aggregations
Summary queries over a large DirectQuery table can be answered from memory instead of the source thanks to this semantic model feature: it keeps a concealed summary table cached and sends qualifying queries there, while anything needing fine detail still goes back to the source.
Related terms
- SUMMARIZECOLUMNS
Groups by whichever columns you list, returning a summary table; filter tables and named expressions can be added. Helpers like ROLLUPADDISSUBTOTAL only function within it, and rows whose expressions are all BLANK get dropped.