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fix(datasource): keep stats absent when collect_stats is false #21149

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Merged
xudong963 merged 3 commits into from
Apr 7, 2026
+278 −54
Merged

fix(datasource): keep stats absent when collect_stats is false #21149

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23fa3f6
fix(datasource): keep stats absent when collect_stats is false
kumarUjjawal Mar 25, 2026
b9048eb
fix(datasource): preserve limit pruning without summary stats
kumarUjjawal Apr 2, 2026
5779fd3
trigger ci
kosiew Apr 4, 2026
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177 changes: 166 additions & 11 deletions datafusion/datasource/src/statistics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -320,16 +320,19 @@ pub async fn get_statistics_with_limit(
file.statistics = Some(Arc::clone(&file_stats));
result_files.push(file);

// First file, we set them directly from the file statistics.
num_rows = file_stats.num_rows;
total_byte_size = file_stats.total_byte_size;
for (index, file_column) in
file_stats.column_statistics.clone().into_iter().enumerate()
{
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.cast_to_sum_type();
if collect_stats {
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@kosiew kosiew Apr 2, 2026

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Thanks for fixing the returned summary here. I think this introduces a separate issue in the limit path though.

get_statistics_with_limit still relies on num_rows to decide whether it can stop early. With collect_stats=false, num_rows now stays Absent, so conservative_num_rows falls back to usize::MIN and we keep scanning the stream instead of stopping early.

Before this change, a known first-file row count could still let us stop after the first file. With this patch, even something like limit=0 can continue reading later files.

Could we preserve a separate row-count accumulator, or at least keep the first-file row count around for the limit check, while still returning a bare Statistics value when collect_stats is false? I think we should also add a regression test for collect_stats=false with a limit so this behavior is locked in.

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@kosiew kosiew Apr 2, 2026

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Small refactor suggestion. It may be worth extracting the "seed stats from first file" logic into a helper that can optionally populate the summary accumulator.

This block and the later merge loop now both need to stay in sync on fields like byte_size and the sum_value casting. Pulling that into one place would make future stats-field additions a bit less likely to drift.

// First file, we set them directly from the file statistics.
num_rows = file_stats.num_rows;
total_byte_size = file_stats.total_byte_size;
for (index, file_column) in
file_stats.column_statistics.clone().into_iter().enumerate()
{
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.cast_to_sum_type();
col_stats_set[index].byte_size = file_column.byte_size;
}
}

// If the number of rows exceeds the limit, we can stop processing
Expand Down Expand Up @@ -520,6 +523,39 @@ mod tests {
}
}

fn test_schema() -> SchemaRef {
Arc::new(Schema::new(vec![Field::new("a", DataType::Int64, true)]))
}

fn make_file_stats(
num_rows: usize,
total_byte_size: usize,
col_stats: ColumnStatistics,
) -> Arc<Statistics> {
Arc::new(Statistics {
num_rows: Precision::Exact(num_rows),
total_byte_size: Precision::Exact(total_byte_size),
column_statistics: vec![col_stats],
})
}

fn rich_col_stats(
null_count: usize,
min: i64,
max: i64,
sum: i64,
byte_size: usize,
) -> ColumnStatistics {
ColumnStatistics {
null_count: Precision::Exact(null_count),
max_value: Precision::Exact(ScalarValue::Int64(Some(max))),
min_value: Precision::Exact(ScalarValue::Int64(Some(min))),
distinct_count: Precision::Absent,
sum_value: Precision::Exact(ScalarValue::Int64(Some(sum))),
byte_size: Precision::Exact(byte_size),
}
}

#[tokio::test]
#[expect(deprecated)]
async fn test_get_statistics_with_limit_casts_first_file_sum_to_sum_type()
Expand All @@ -533,7 +569,7 @@ mod tests {
))]);

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

assert_eq!(
stats.column_statistics[0].sum_value,
Expand Down Expand Up @@ -571,4 +607,123 @@ mod tests {

Ok(())
}

#[tokio::test]
#[expect(deprecated)]
async fn get_statistics_with_limit_collect_stats_false_returns_bare_statistics() {
let all_files = stream::iter(vec![
Ok((
PartitionedFile::new("first.parquet", 10),
make_file_stats(0, 0, rich_col_stats(1, 1, 9, 15, 64)),
)),
Ok((
PartitionedFile::new("second.parquet", 20),
make_file_stats(10, 100, rich_col_stats(2, 10, 99, 300, 128)),
)),
]);

let (_files, statistics) =
get_statistics_with_limit(all_files, test_schema(), None, false)
.await
.unwrap();

assert_eq!(statistics.num_rows, Precision::Absent);
assert_eq!(statistics.total_byte_size, Precision::Absent);
assert_eq!(statistics.column_statistics.len(), 1);
assert_eq!(
statistics.column_statistics[0].null_count,
Precision::Absent
);
assert_eq!(statistics.column_statistics[0].max_value, Precision::Absent);
assert_eq!(statistics.column_statistics[0].min_value, Precision::Absent);
assert_eq!(statistics.column_statistics[0].sum_value, Precision::Absent);
assert_eq!(statistics.column_statistics[0].byte_size, Precision::Absent);
}

#[tokio::test]
#[expect(deprecated)]
async fn get_statistics_with_limit_collect_stats_true_aggregates_statistics() {
let all_files = stream::iter(vec![
Ok((
PartitionedFile::new("first.parquet", 10),
make_file_stats(5, 50, rich_col_stats(1, 1, 9, 15, 64)),
)),
Ok((
PartitionedFile::new("second.parquet", 20),
make_file_stats(10, 100, rich_col_stats(2, 10, 99, 300, 128)),
)),
]);

let (_files, statistics) =
get_statistics_with_limit(all_files, test_schema(), None, true)
.await
.unwrap();

assert_eq!(statistics.num_rows, Precision::Exact(15));
assert_eq!(statistics.total_byte_size, Precision::Exact(150));
assert_eq!(
statistics.column_statistics[0].null_count,
Precision::Exact(3)
);
assert_eq!(
statistics.column_statistics[0].min_value,
Precision::Exact(ScalarValue::Int64(Some(1)))
);
assert_eq!(
statistics.column_statistics[0].max_value,
Precision::Exact(ScalarValue::Int64(Some(99)))
);
assert_eq!(
statistics.column_statistics[0].sum_value,
Precision::Exact(ScalarValue::Int64(Some(315)))
);
assert_eq!(
statistics.column_statistics[0].byte_size,
Precision::Exact(192)
);
}

#[tokio::test]
#[expect(deprecated)]
async fn get_statistics_with_limit_collect_stats_true_limit_marks_inexact() {
let all_files = stream::iter(vec![
Ok((
PartitionedFile::new("first.parquet", 10),
make_file_stats(5, 50, rich_col_stats(0, 1, 5, 15, 64)),
)),
Ok((
PartitionedFile::new("second.parquet", 20),
make_file_stats(5, 50, rich_col_stats(1, 6, 10, 40, 64)),
)),
Ok((
PartitionedFile::new("third.parquet", 20),
make_file_stats(5, 50, rich_col_stats(2, 11, 15, 65, 64)),
)),
]);

let (files, statistics) =
get_statistics_with_limit(all_files, test_schema(), Some(8), true)
.await
.unwrap();

assert_eq!(files.len(), 2);
assert_eq!(statistics.num_rows, Precision::Inexact(10));
assert_eq!(statistics.total_byte_size, Precision::Inexact(100));
assert_eq!(
statistics.column_statistics[0].min_value,
Precision::Inexact(ScalarValue::Int64(Some(1)))
);
assert_eq!(
statistics.column_statistics[0].max_value,
Precision::Inexact(ScalarValue::Int64(Some(10)))
);
assert_eq!(
statistics.column_statistics[0].sum_value,
Precision::Inexact(ScalarValue::Int64(Some(55)))
);
assert_eq!(
statistics.column_statistics[0].byte_size,
Precision::Inexact(128)
);
}
}
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