I get overflow error on sum and multiplication - I can see the underlying type as decimal and my sum (calculated independently in excel) is around 48 trillion, hardly a big number. How can I ensure all underlying type are proper 64bit floats ?
Quicksight uses 64 bits for DECIMAL types. See Supported data types and values - Amazon QuickSight
DECIMALfield in imported data, QuickSight uses a field length of 8 bytes.
However, when you use multiplication or sum, it is possible that the result exceeds the range of 64-bit values and hence you get the overflow error.