aweltsch commented on code in PR #7021:
URL: https://github.com/apache/arrow-rs/pull/7021#discussion_r1947492543
##########
arrow-cast/src/cast/decimal.rs:
##########
@@ -76,6 +76,54 @@ where
}
}
+pub(crate) fn convert_to_smaller_scale_decimal_same_type<T>(
+ array: &PrimitiveArray<T>,
+ input_precision: u8,
+ input_scale: i8,
+ output_precision: u8,
+ output_scale: i8,
+ cast_options: &CastOptions,
+) -> Result<PrimitiveArray<T>, ArrowError>
+where
+ T: DecimalType,
+ T::Native: DecimalCast + ArrowNativeTypeOp,
+{
+ let delta_scale = input_scale - output_scale;
+ // if the reudction of the input number through scaling (dividing) is
greater
+ // than a possible precision loss (plus potential increase via rounding)
every input number will fit into the output type
+ let is_infallible_cast = (input_precision as i8) - delta_scale <
(output_precision as i8);
+
+ if is_infallible_cast {
Review Comment:
Thanks for the valuable feedback! Originally I thought we can only apply
this to same type casts, but I think this can also be applied between decimal
types since we're checking the "validity" condition based on the output
precision, so from what I can tell we should be able to merge the functions.
:+1:
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
