Mastering Microsoft Power BI

Fact and dimension queries

For larger datasets with multiple fact tables, most M queries will access a single SQL view, apply minimal to no transformations, and then expose the results of this query to the data model as a dimension or fact table. For import mode datasets, the M query is executed upon a scheduled refresh and the query results are loaded into a compressed, columnar format. For DirectQuery mode datasets, the M queries with the Enable load property set only define the SQL statement representing the given dimension or fact tables. The DirectQuery data source will utilize these SQL statements to create SQL queries necessary to resolve report queries, such as joining the Internet Sales query with the Product query.