DecimalAverager

datafusion_physical_expr::aggregate::utils

Struct DecimalAverager 

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pub struct DecimalAverager<T>
where
    T: DecimalType,
{
    sum_mul: <T as ArrowPrimitiveType>::Native,
    target_mul: <T as ArrowPrimitiveType>::Native,
    target_precision: u8,
    target_scale: i8,
}
Expand description

Computes averages for Decimal128/Decimal256 values, checking for overflow

This is needed because different precisions for Decimal128/Decimal256 can store different ranges of values and thus sum/count may not fit in the target type.

For example, the precision is 3, the max of value is 999 and the min value is -999

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§sum_mul: <T as ArrowPrimitiveType>::Native§target_mul: <T as ArrowPrimitiveType>::Native§target_precision: u8§target_scale: i8

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impl<T> DecimalAverager<T>
where T: DecimalType,

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pub fn try_new( sum_scale: i8, target_precision: u8, target_scale: i8, ) -> Result<DecimalAverager<T>, DataFusionError>

Create a new DecimalAverager:

  • sum_scale: the scale of sum values passed to Self::avg
  • target_precision: the output precision
  • target_scale: the output scale

Errors if the resulting data can not be stored

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pub fn avg( &self, sum: <T as ArrowPrimitiveType>::Native, count: <T as ArrowPrimitiveType>::Native, ) -> Result<<T as ArrowPrimitiveType>::Native, DataFusionError>

Returns the sum/count as a i128/i256 Decimal128/Decimal256 with target_scale and target_precision and reporting overflow.

  • sum: The total sum value stored as Decimal128 with sum_scale (passed to Self::try_new)
  • count: total count, stored as a i128/i256 (NOT a Decimal128/Decimal256 value)

Auto Trait Implementations§

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impl<T> Freeze for DecimalAverager<T>
where <T as ArrowPrimitiveType>::Native: Freeze,

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impl<T> RefUnwindSafe for DecimalAverager<T>
where <T as ArrowPrimitiveType>::Native: RefUnwindSafe,

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impl<T> Send for DecimalAverager<T>

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impl<T> Sync for DecimalAverager<T>

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impl<T> Unpin for DecimalAverager<T>
where <T as ArrowPrimitiveType>::Native: Unpin,

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impl<T> UnwindSafe for DecimalAverager<T>
where <T as ArrowPrimitiveType>::Native: UnwindSafe,

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impl<T> Any for T
where T: 'static + ?Sized,

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where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

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impl<T> From<T> for T

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fn from(t: T) -> T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided [Span], returning an Instrumented wrapper. Read more
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