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fix(stats): widen sum_value integer arithmetic to SUM-compatible types #20865

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fix(stats): widen sum_value integer arithmetic to SUM-compatible types #20865

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94 changes: 91 additions & 3 deletions datafusion/common/src/stats.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,14 @@ impl Precision<usize> {
}

impl Precision<ScalarValue> {
fn sum_data_type(data_type: &DataType) -> DataType {
match data_type {
DataType::Int8 | DataType::Int16 | DataType::Int32 => DataType::Int64,
DataType::UInt8 | DataType::UInt16 | DataType::UInt32 => DataType::UInt64,
_ => data_type.clone(),
}
}

/// Calculates the sum of two (possibly inexact) [`ScalarValue`] values,
/// conservatively propagating exactness information. If one of the input
/// values is [`Precision::Absent`], the result is `Absent` too.
Expand All @@ -198,6 +206,46 @@ impl Precision<ScalarValue> {
}
}

/// Casts integer values to the wider SQL `SUM` return type.
///
/// This narrows overflow risk when `sum_value` statistics are merged:
/// `Int8/Int16/Int32 -> Int64` and `UInt8/UInt16/UInt32 -> UInt64`.
pub fn cast_to_sum_type(&self) -> Precision<ScalarValue> {
match self {
Precision::Exact(value) => {
let source_type = value.data_type();
let target_type = Self::sum_data_type(&source_type);
if source_type == target_type {
Precision::Exact(value.clone())
} else {
value
.cast_to(&target_type)
.map(Precision::Exact)
.unwrap_or(Precision::Absent)
}
}
Precision::Inexact(value) => {
let source_type = value.data_type();
let target_type = Self::sum_data_type(&source_type);
if source_type == target_type {
Precision::Inexact(value.clone())
} else {
value
.cast_to(&target_type)
.map(Precision::Inexact)
.unwrap_or(Precision::Absent)
}
}
Precision::Absent => Precision::Absent,
}
}

/// SUM-style addition with integer widening to match SQL `SUM` return
/// types for smaller integral inputs.
pub fn add_for_sum(&self, other: &Precision<ScalarValue>) -> Precision<ScalarValue> {
self.cast_to_sum_type().add(&other.cast_to_sum_type())
}

/// Calculates the difference of two (possibly inexact) [`ScalarValue`] values,
/// conservatively propagating exactness information. If one of the input
/// values is [`Precision::Absent`], the result is `Absent` too.
Expand Down Expand Up @@ -636,7 +684,8 @@ impl Statistics {
col_stats.null_count = col_stats.null_count.add(&item_col_stats.null_count);
col_stats.max_value = col_stats.max_value.max(&item_col_stats.max_value);
col_stats.min_value = col_stats.min_value.min(&item_col_stats.min_value);
col_stats.sum_value = col_stats.sum_value.add(&item_col_stats.sum_value);
col_stats.sum_value =
col_stats.sum_value.add_for_sum(&item_col_stats.sum_value);
col_stats.distinct_count = Precision::Absent;
col_stats.byte_size = col_stats.byte_size.add(&item_col_stats.byte_size);
}
Expand Down Expand Up @@ -948,6 +997,45 @@ mod tests {
assert_eq!(precision.add(&Precision::Absent), Precision::Absent);
}

#[test]
fn test_add_for_sum_scalar_integer_widening() {
let precision = Precision::Exact(ScalarValue::Int32(Some(42)));

assert_eq!(
precision.add_for_sum(&Precision::Exact(ScalarValue::Int32(Some(23)))),
Precision::Exact(ScalarValue::Int64(Some(65))),
);
assert_eq!(
precision.add_for_sum(&Precision::Inexact(ScalarValue::Int32(Some(23)))),
Precision::Inexact(ScalarValue::Int64(Some(65))),
);
}

#[test]
fn test_add_for_sum_prevents_int32_overflow() {
let lhs = Precision::Exact(ScalarValue::Int32(Some(i32::MAX)));
let rhs = Precision::Exact(ScalarValue::Int32(Some(1)));

assert_eq!(
lhs.add_for_sum(&rhs),
Precision::Exact(ScalarValue::Int64(Some(i64::from(i32::MAX) + 1))),
);
}

#[test]
fn test_add_for_sum_scalar_unsigned_integer_widening() {
let precision = Precision::Exact(ScalarValue::UInt32(Some(42)));

assert_eq!(
precision.add_for_sum(&Precision::Exact(ScalarValue::UInt32(Some(23)))),
Precision::Exact(ScalarValue::UInt64(Some(65))),
);
assert_eq!(
precision.add_for_sum(&Precision::Inexact(ScalarValue::UInt32(Some(23)))),
Precision::Inexact(ScalarValue::UInt64(Some(65))),
);
}

#[test]
fn test_sub() {
let precision1 = Precision::Exact(42);
Expand Down Expand Up @@ -1193,7 +1281,7 @@ mod tests {
);
assert_eq!(
col1_stats.sum_value,
Precision::Exact(ScalarValue::Int32(Some(1100)))
Precision::Exact(ScalarValue::Int64(Some(1100)))
); // 500 + 600

let col2_stats = &summary_stats.column_statistics[1];
Expand All @@ -1208,7 +1296,7 @@ mod tests {
);
assert_eq!(
col2_stats.sum_value,
Precision::Exact(ScalarValue::Int32(Some(2200)))
Precision::Exact(ScalarValue::Int64(Some(2200)))
); // 1000 + 1200
}

Expand Down
81 changes: 78 additions & 3 deletions datafusion/datasource/src/statistics.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -293,7 +293,7 @@ fn sort_columns_from_physical_sort_exprs(
since = "47.0.0",
note = "Please use `get_files_with_limit` and `compute_all_files_statistics` instead"
)]
#[expect(unused)]
#[cfg_attr(not(test), expect(unused))]
pub async fn get_statistics_with_limit(
all_files: impl Stream<Item = Result<(PartitionedFile, Arc<Statistics>)>>,
file_schema: SchemaRef,
Expand Down Expand Up @@ -329,7 +329,7 @@ pub async fn get_statistics_with_limit(
col_stats_set[index].null_count = file_column.null_count;
col_stats_set[index].max_value = file_column.max_value;
col_stats_set[index].min_value = file_column.min_value;
col_stats_set[index].sum_value = file_column.sum_value;
col_stats_set[index].sum_value = file_column.sum_value.cast_to_sum_type();
}

// If the number of rows exceeds the limit, we can stop processing
Expand Down Expand Up @@ -374,7 +374,7 @@ pub async fn get_statistics_with_limit(
col_stats.null_count = col_stats.null_count.add(file_nc);
col_stats.max_value = col_stats.max_value.max(file_max);
col_stats.min_value = col_stats.min_value.min(file_min);
col_stats.sum_value = col_stats.sum_value.add(file_sum);
col_stats.sum_value = col_stats.sum_value.add_for_sum(file_sum);
col_stats.byte_size = col_stats.byte_size.add(file_sbs);
}

Expand Down Expand Up @@ -497,3 +497,78 @@ pub fn add_row_stats(
) -> Precision<usize> {
file_num_rows.add(&num_rows)
}

#[cfg(test)]
mod tests {
use super::*;
use crate::PartitionedFile;
use arrow::datatypes::{DataType, Field, Schema};
use futures::stream;

fn file_stats(sum: u32) -> Statistics {
Statistics {
num_rows: Precision::Exact(1),
total_byte_size: Precision::Exact(4),
column_statistics: vec![ColumnStatistics {
null_count: Precision::Exact(0),
max_value: Precision::Exact(ScalarValue::UInt32(Some(sum))),
min_value: Precision::Exact(ScalarValue::UInt32(Some(sum))),
sum_value: Precision::Exact(ScalarValue::UInt32(Some(sum))),
distinct_count: Precision::Exact(1),
byte_size: Precision::Exact(4),
}],
}
}

#[tokio::test]
#[expect(deprecated)]
async fn test_get_statistics_with_limit_casts_first_file_sum_to_sum_type()
-> Result<()> {
let schema =
Arc::new(Schema::new(vec![Field::new("c1", DataType::UInt32, true)]));

let files = stream::iter(vec![Ok((
PartitionedFile::new("f1.parquet", 1),
Arc::new(file_stats(100)),
))]);

let (_group, stats) =
get_statistics_with_limit(files, schema, None, false).await?;

assert_eq!(
stats.column_statistics[0].sum_value,
Precision::Exact(ScalarValue::UInt64(Some(100)))
);

Ok(())
}

#[tokio::test]
#[expect(deprecated)]
async fn test_get_statistics_with_limit_merges_sum_with_unsigned_widening()
-> Result<()> {
let schema =
Arc::new(Schema::new(vec![Field::new("c1", DataType::UInt32, true)]));

let files = stream::iter(vec![
Ok((
PartitionedFile::new("f1.parquet", 1),
Arc::new(file_stats(100)),
)),
Ok((
PartitionedFile::new("f2.parquet", 1),
Arc::new(file_stats(200)),
)),
]);

let (_group, stats) =
get_statistics_with_limit(files, schema, None, true).await?;

assert_eq!(
stats.column_statistics[0].sum_value,
Precision::Exact(ScalarValue::UInt64(Some(300)))
);

Ok(())
}
}
42 changes: 37 additions & 5 deletions datafusion/physical-expr/src/projection.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -693,12 +693,15 @@ impl ProjectionExprs {
Precision::Absent
};

let sum_value = Precision::<ScalarValue>::from(stats.num_rows)
.cast_to(&value.data_type())
.ok()
.map(|row_count| {
Precision::Exact(value.clone()).multiply(&row_count)
let widened_sum = Precision::Exact(value.clone()).cast_to_sum_type();
let sum_value = widened_sum
.get_value()
.and_then(|sum| {
Precision::<ScalarValue>::from(stats.num_rows)
.cast_to(&sum.data_type())
.ok()
})
.map(|row_count| widened_sum.multiply(&row_count))
.unwrap_or(Precision::Absent);

ColumnStatistics {
Expand Down Expand Up @@ -2866,6 +2869,35 @@ pub(crate) mod tests {
Ok(())
}

#[test]
fn test_project_statistics_with_i32_literal_sum_widens_to_i64() -> Result<()> {
let input_stats = get_stats();
let input_schema = get_schema();

let projection = ProjectionExprs::new(vec![
ProjectionExpr {
expr: Arc::new(Literal::new(ScalarValue::Int32(Some(10)))),
alias: "constant".to_string(),
},
ProjectionExpr {
expr: Arc::new(Column::new("col0", 0)),
alias: "num".to_string(),
},
]);

let output_stats = projection.project_statistics(
input_stats,
&projection.project_schema(&input_schema)?,
)?;

assert_eq!(
output_stats.column_statistics[0].sum_value,
Precision::Exact(ScalarValue::Int64(Some(50)))
);

Ok(())
}

// Test statistics calculation for NULL literal (constant NULL column)
#[test]
fn test_project_statistics_with_null_literal() -> Result<()> {
Expand Down
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