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Fail correctly when Python UDF decimal result overflows #28925

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Merged
findepi merged 1 commit into from
Mar 30, 2026
Merged

Fail correctly when Python UDF decimal result overflows #28925

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15 changes: 12 additions & 3 deletions plugin/trino-functions-python/src/main/java/io/trino/plugin/functions/python/TrinoTypes.java
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@
import static io.trino.spi.type.TypeUtils.writeNativeValue;
import static java.lang.Math.toIntExact;
import static java.math.RoundingMode.HALF_UP;
import static java.util.Objects.requireNonNullElse;

final class TrinoTypes
{
Expand Down Expand Up @@ -381,9 +382,17 @@ public static Object binaryToJava(Type type, SliceInput input)
case MapType mapType -> binaryMapToJava(mapType, input);
case DecimalType decimalType -> {
BigDecimal decimal = new BigDecimal(input.readSlice(input.readInt()).toStringUtf8());
yield decimalType.isShort()
? encodeShortScaledValue(decimal, decimalType.getScale(), HALF_UP)
: encodeScaledValue(decimal, decimalType.getScale(), HALF_UP);
try {
yield decimalType.isShort()
? encodeShortScaledValue(decimal, decimalType.getScale(), HALF_UP)
: encodeScaledValue(decimal, decimalType.getScale(), HALF_UP);
}
catch (ArithmeticException e) {
throw new TrinoException(
FUNCTION_IMPLEMENTATION_ERROR,
"Function result cannot be converted to %s: %s".formatted(decimalType.getDisplayName(), requireNonNullElse(e.getMessage(), e)),
e);
}
}
case TimeType timeType -> {
long micros = roundMicros(input.readLong(), timeType.getPrecision()) % MICROSECONDS_PER_DAY;
Expand Down
31 changes: 31 additions & 0 deletions ...-functions-python/src/test/java/io/trino/plugin/functions/python/TestPythonFunctions.java
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Original file line number Diff line number Diff line change
Expand Up @@ -898,6 +898,37 @@ assert str(x) == '12345678901234567890.12340'
SELECT test_decimal_long(12345678901234567890.1234)
"""))
.matches("VALUES cast(1524148134430814813443.07447 AS decimal(38, 5))");

String realToDecimalInPython =
"""
WITH FUNCTION test_cast_real_to_decimal(x real)
RETURNS decimal(38, 5)
LANGUAGE PYTHON
WITH (handler = 'test')
AS $$
from decimal import Decimal
def test(x):
return Decimal.from_float(x)
$$
""";

// underflow
assertThat(assertions.query(realToDecimalInPython + "SELECT test_cast_real_to_decimal(REAL '1e-17')"))
.matches("VALUES CAST('0' AS decimal(38, 5))");

// overflow
assertThat(assertions.query(realToDecimalInPython + "SELECT test_cast_real_to_decimal(REAL '1e+34')"))
.failure().hasMessage("Function result cannot be converted to decimal(38,5): Decimal overflow");

// NaN
assertThat(assertions.query( realToDecimalInPython + "SELECT test_cast_real_to_decimal(REAL 'NaN')"))
.failure().hasMessage("Failed to convert Python result type 'decimal.Decimal' to Trino type DECIMAL: ValueError: Decimal is not finite: NaN");

// Infinity
assertThat(assertions.query(realToDecimalInPython + "SELECT test_cast_real_to_decimal(REAL '-Infinity')"))
.failure().hasMessage("Failed to convert Python result type 'decimal.Decimal' to Trino type DECIMAL: ValueError: Decimal is not finite: -Infinity");
assertThat(assertions.query( realToDecimalInPython + "SELECT test_cast_real_to_decimal(REAL '+Infinity')"))
.failure().hasMessage("Failed to convert Python result type 'decimal.Decimal' to Trino type DECIMAL: ValueError: Decimal is not finite: Infinity");
}

@Test
Expand Down