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fix: trunc function with precision uses round instead of trunc semantics #19794

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Merged
Jefffrey merged 2 commits into from
Jan 16, 2026
Merged

fix: trunc function with precision uses round instead of trunc semantics #19794

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17cf190
fix: trunc function with precision uses round instead of trunc semantics
kumarUjjawal Jan 13, 2026
2c4065c
revert the deleted assertion
kumarUjjawal Jan 15, 2026
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12 changes: 6 additions & 6 deletions datafusion/functions/src/math/trunc.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -202,12 +202,12 @@ fn trunc(args: &[ArrayRef]) -> Result<ArrayRef> {

fn compute_truncate32(x: f32, y: i64) -> f32 {
let factor = 10.0_f32.powi(y as i32);
(x * factor).round() / factor
(x * factor).trunc() / factor
}

fn compute_truncate64(x: f64, y: i64) -> f64 {
let factor = 10.0_f64.powi(y as i32);
(x * factor).round() / factor
(x * factor).trunc() / factor
}

#[cfg(test)]
Expand Down Expand Up @@ -238,9 +238,9 @@ mod test {

assert_eq!(floats.len(), 5);
assert_eq!(floats.value(0), 15.0);
assert_eq!(floats.value(1), 1_234.268);
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@martin-g martin-g Jan 15, 2026

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why is this assertion removed ?

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@kumarUjjawal kumarUjjawal Jan 15, 2026

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Oops, I might have accidently deleted the line during editing.

assert_eq!(floats.value(1), 1_234.267);
assert_eq!(floats.value(2), 1_233.12);
assert_eq!(floats.value(3), 3.312_98);
assert_eq!(floats.value(3), 3.312_97);
assert_eq!(floats.value(4), -21.123_4);
}

Expand All @@ -263,9 +263,9 @@ mod test {

assert_eq!(floats.len(), 5);
assert_eq!(floats.value(0), 5.0);
assert_eq!(floats.value(1), 234.268);
assert_eq!(floats.value(1), 234.267);
assert_eq!(floats.value(2), 123.12);
assert_eq!(floats.value(3), 123.312_98);
assert_eq!(floats.value(3), 123.312_97);
assert_eq!(floats.value(4), -321.123_1);
}

Expand Down
2 changes: 1 addition & 1 deletion datafusion/sqllogictest/test_files/scalar.slt
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Expand Up @@ -1165,7 +1165,7 @@ from small_floats;
----
0.447 0.4 0.447
0.707 0.7 0.707
0.837 0.8 0.837
0.836 0.8 0.836
1 1 1

## bitwise and
Expand Down