A retailer is expanding globally and needs Amazon QuickSight to compute currency exchange rates for financial reports with four-decimal precision. The calculations must be precomputed and stored in SPICE for fast, parallel, in-memory access. Where should the engineer define the calculated field to satisfy these requirements?

Defining the calculated field in the dataset ensures that the currency exchange rate calculations are precomputed and stored in SPICE. This allows for fast, parallel, in-memory access across all analyses, visuals, and dashboards that use this dataset, meeting the performance and precision requirements. If the calculation were defined in the analysis, visual, or dashboard, it would be computed at query time for that specific context, not precomputed and stored in SPICE, which would negate the performance benefits and might lead to inconsistent results across different reports.