tustvold commented on code in PR #2857:
URL: https://github.com/apache/arrow-rs/pull/2857#discussion_r992892010
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arrow-array/src/array/primitive_array.rs:
##########
@@ -827,9 +831,178 @@ impl<T: ArrowPrimitiveType> From<ArrayData> for
PrimitiveArray<T> {
}
}
+impl<T: DecimalType + ArrowPrimitiveType> PrimitiveArray<T> {
+ /// Returns a Decimal array with the same data as self, with the
+ /// specified precision.
+ ///
+ /// Returns an Error if:
+ /// 1. `precision` is larger than `T:MAX_PRECISION`
+ /// 2. `scale` is larger than `T::MAX_SCALE`
+ /// 3. `scale` is > `precision`
+ pub fn with_precision_and_scale(
+ self,
+ precision: u8,
+ scale: u8,
+ ) -> Result<Self, ArrowError>
+ where
+ Self: Sized,
+ {
+ // validate precision and scale
+ self.validate_precision_scale(precision, scale)?;
+
+ // Ensure that all values are within the requested
+ // precision. For performance, only check if the precision is
+ // decreased
+ let p = self.precision()?;
+ if precision < p {
+ self.validate_decimal_precision(precision)?;
+ }
+
+ // safety: self.data is valid DataType::Decimal as checked above
+ let new_data_type = T::TYPE_CONSTRUCTOR(precision, scale);
+ let data = self.data().clone().into_builder().data_type(new_data_type);
+
+ // SAFETY
+ // Validated data above
+ Ok(unsafe { data.build_unchecked().into() })
+ }
+
+ /// Returns a Decimal array with the same data as self, with the
+ /// specified precision.
+ ///
+ /// # Safety
+ ///
+ /// This doesn't validate decimal values with specified precision.
+ pub unsafe fn unchecked_with_precision_and_scale(
Review Comment:
The move to PrimitiveArray implicitly means away from validating the
contents for overflow, as any value of the underlying primitive is permitted.
I think we should therefore make this safe, and remove any value validation
except for when this method is explicitly called by the user, as an opt-in
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