Dimensions and metrics are calculated on the fly, and computed against your warehouse. Crawling this heavy data is not only expensive, but also painfully slow. There’s no need for that to happen every time you run a query. Whaly uses pre-aggregation by creating a table of pre-aggregated results, where only a few lines are scanned. With this table, you can crawl the pre-aggregated results on a need basis. Not only does this turbo-boost your speed, this also ensures that you’re optimized around data warehouse cost, and you won’t get a scary bill at the end of the month.