If you are using multidimensional cubes, you can opt for the ROLAP mode:
ROLAP - The ROLAP storage mode causes the aggregations of the partition to be stored in indexed views in the relational database that was specified in the partition's data source. Unlike the MOLAP storage mode, ROLAP does not cause a copy of the source data to be stored in the Analysis Services data folders. Instead, when results cannot be derived from the query cache, the indexed views in the data source is accessed to answer queries. Query response is generally slower with ROLAP storage than with the MOLAP or HOLAP storage modes. Processing time is also typically slower with ROLAP. However, ROLAP enables users to view data in real time and can save storage space when you are working with large datasets that are infrequently queried, such as purely historical data.
If you rather go SSAS Tabular, direct query can be option:
Analysis Services lets you retrieve data and create reports from a tabular model by retrieving data and aggregates directly from a relational database system, using DirectQuery mode. (Direct Query is an enterprise feature)