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[branch-50] Extend datatype semantic equality check to include timestamps (#17777) #18129

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Merged
alamb merged 3 commits into from
Oct 20, 2025
Merged

[branch-50] Extend datatype semantic equality check to include timestamps (#17777) #18129

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77155a1
Extend datatype semantic equality check to include timestamps (#17777)
shivbhatia10 Sep 28, 2025
c431fec
remove incorectly backported test
alamb Oct 19, 2025
103bc5f
branch 'apache/branch-50' into hareshkh/datatype-semantic-equality-c…
alamb Oct 19, 2025
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36 changes: 35 additions & 1 deletion datafusion/common/src/dfschema.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -747,7 +747,8 @@ impl DFSchema {
}

/// Returns true of two [`DataType`]s are semantically equal (same
/// name and type), ignoring both metadata and nullability, and decimal precision/scale.
/// name and type), ignoring both metadata and nullability, decimal precision/scale,
/// and timezone time units/timezones.
///
/// request to upstream: <https://github.com/apache/arrow-rs/issues/3199>
pub fn datatype_is_semantically_equal(dt1: &DataType, dt2: &DataType) -> bool {
Expand Down Expand Up @@ -806,6 +807,10 @@ impl DFSchema {
DataType::Decimal256(_l_precision, _l_scale),
DataType::Decimal256(_r_precision, _r_scale),
) => true,
(
DataType::Timestamp(_l_time_unit, _l_timezone),
DataType::Timestamp(_r_time_unit, _r_timezone),
) => true,
_ => dt1 == dt2,
}
}
Expand Down Expand Up @@ -1596,6 +1601,35 @@ mod tests {
&DataType::Int16
));

// Succeeds if decimal precision and scale are different
assert!(DFSchema::datatype_is_semantically_equal(

@alamb alamb Oct 19, 2025

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these decimal tests appear to have been backported from main without the corresponding code. I will remove them

&DataType::Decimal32(1, 2),
&DataType::Decimal32(2, 1),
));

assert!(DFSchema::datatype_is_semantically_equal(
&DataType::Decimal64(1, 2),
&DataType::Decimal64(2, 1),
));

assert!(DFSchema::datatype_is_semantically_equal(
&DataType::Decimal128(1, 2),
&DataType::Decimal128(2, 1),
));

assert!(DFSchema::datatype_is_semantically_equal(
&DataType::Decimal256(1, 2),
&DataType::Decimal256(2, 1),
));

// Any two timestamp types should match
assert!(DFSchema::datatype_is_semantically_equal(
&DataType::Timestamp(
arrow::datatypes::TimeUnit::Microsecond,
Some("UTC".into())
),
&DataType::Timestamp(arrow::datatypes::TimeUnit::Millisecond, None),
));
// Test lists

// Succeeds if both have the same element type, disregards names and nullability
Expand Down
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