Dandandan commented on code in PR #6904:
URL: https://github.com/apache/arrow-datafusion/pull/6904#discussion_r1258633126
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datafusion/physical-expr/src/aggregate/min_max.rs:
##########
@@ -1022,6 +1112,224 @@ impl RowAccumulator for MinRowAccumulator {
}
}
+trait MinMax {
+ fn min() -> Self;
+ fn max() -> Self;
+}
+
+impl MinMax for u8 {
+ fn min() -> Self {
+ u8::MIN
+ }
+ fn max() -> Self {
+ u8::MAX
+ }
+}
+impl MinMax for i8 {
+ fn min() -> Self {
+ i8::MIN
+ }
+ fn max() -> Self {
+ i8::MAX
+ }
+}
+impl MinMax for u16 {
+ fn min() -> Self {
+ u16::MIN
+ }
+ fn max() -> Self {
+ u16::MAX
+ }
+}
+impl MinMax for i16 {
+ fn min() -> Self {
+ i16::MIN
+ }
+ fn max() -> Self {
+ i16::MAX
+ }
+}
+impl MinMax for u32 {
+ fn min() -> Self {
+ u32::MIN
+ }
+ fn max() -> Self {
+ u32::MAX
+ }
+}
+impl MinMax for i32 {
+ fn min() -> Self {
+ i32::MIN
+ }
+ fn max() -> Self {
+ i32::MAX
+ }
+}
+impl MinMax for i64 {
+ fn min() -> Self {
+ i64::MIN
+ }
+ fn max() -> Self {
+ i64::MAX
+ }
+}
+impl MinMax for u64 {
+ fn min() -> Self {
+ u64::MIN
+ }
+ fn max() -> Self {
+ u64::MAX
+ }
+}
+impl MinMax for f32 {
+ fn min() -> Self {
+ f32::MIN
+ }
+ fn max() -> Self {
+ f32::MAX
+ }
+}
+impl MinMax for f64 {
+ fn min() -> Self {
+ f64::MIN
+ }
+ fn max() -> Self {
+ f64::MAX
+ }
+}
+impl MinMax for i128 {
+ fn min() -> Self {
+ i128::MIN
+ }
+ fn max() -> Self {
+ i128::MAX
+ }
+}
+
+/// An accumulator to compute the min or max of [`PrimitiveArray<T>`].
+/// Stores values as native/primitive type
+#[derive(Debug)]
+struct MinMaxGroupsPrimitiveAccumulator<T, const MIN: bool>
+where
+ T: ArrowNumericType + Send,
+ T::Native: MinMax,
+{
+ /// Min/max per group, stored as the native type
+ min_max: Vec<T::Native>,
+
+ /// Track nulls in the input / filters
+ null_state: NullState,
+
+ /// The output datatype (needed for decimal precision/scale)
+ data_type: DataType,
+}
+
+impl<T, const MIN: bool> MinMaxGroupsPrimitiveAccumulator<T, MIN>
+where
+ T: ArrowNumericType + Send,
+ T::Native: MinMax,
+{
+ pub fn new(data_type: &DataType) -> Self {
+ debug!(
+ "MinMaxGroupsPrimitiveAccumulator ({}, {})",
+ std::any::type_name::<T>(),
+ MIN,
+ );
+
+ Self {
+ min_max: vec![],
+ null_state: NullState::new(),
+ data_type: data_type.clone(),
+ }
+ }
+}
+
+impl<T, const MIN: bool> GroupsAccumulator for
MinMaxGroupsPrimitiveAccumulator<T, MIN>
+where
+ T: ArrowNumericType + Send,
+ T::Native: MinMax,
+{
+ fn update_batch(
+ &mut self,
+ values: &[ArrayRef],
+ group_indices: &[usize],
+ opt_filter: Option<&arrow_array::BooleanArray>,
+ total_num_groups: usize,
+ ) -> Result<()> {
+ assert_eq!(values.len(), 1, "single argument to update_batch");
+ let values = values.get(0).unwrap().as_primitive::<T>();
+
+ self.min_max.resize_with(total_num_groups, || {
Review Comment:
This could use `resize` instead of `resize_with`
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