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We have a Kimball-style star schema data mart. We have tens of millions of rows with a variety of integer and decimal data types. We are performing aggregating SELECT queries either over the entire data in the table or over a significant slice of data. Only a single result row is expected as there is no GROUP BY clause. We are not using SQL Server Analysis Services, only the relational engine.
Performance is disproportionately slow (observed at 15x slower than after applying workaround). Performance appears to degrade as more columns are added.