Which method provides a balance of cost control and performance for refreshing a dashboard tracking retail store metrics?

Using a nightly batch job to save the necessary values in a table that is overwritten with each update is an effective method for balancing cost control and performance in the context of refreshing a dashboard tracking retail store metrics.

This approach allows for scheduled data processing, which can be optimized for performance by running during off-peak hours. It ensures that the dashboard is updated regularly with complete and refreshed data without the overhead of constant real-time data processing, which could lead to increased operational costs and resource consumption. By creating a table with the required metrics specifically for the dashboard, you streamline data access, leading to faster load times and improved user experience.

The batch processing method also allows for more complex data transformations and aggregations to be performed in one go, providing more comprehensive insights at each refresh cycle. Overall, it strikes a good balance between maintaining up-to-date metrics and managing the costs associated with more frequent updates.