Return error if value scale is different from schema scale

lib/debezium/converters/decimal.go

@@ -2,58 +2,24 @@ package converters
 
 import (
 	"fmt"
-	"log/slog"
 
 	"github.com/artie-labs/transfer/lib/debezium"
 	"github.com/artie-labs/transfer/lib/debezium/converters"
 	"github.com/artie-labs/transfer/lib/typing"
 	"github.com/cockroachdb/apd/v3"
 )
 
-// decimalWithNewExponent takes a [*apd.Decimal] and returns a new [*apd.Decimal] with a the given exponent.
-// If the new exponent is less precise then the extra digits will be truncated.
-func decimalWithNewExponent(decimal *apd.Decimal, newExponent int32) *apd.Decimal {
-	exponentDelta := newExponent - decimal.Exponent // Exponent is negative.
-
-	if exponentDelta == 0 {
-		return new(apd.Decimal).Set(decimal)
-	}
-
-	coefficient := new(apd.BigInt).Set(&decimal.Coeff)
-
-	if exponentDelta < 0 {
-		multiplier := new(apd.BigInt).Exp(apd.NewBigInt(10), apd.NewBigInt(int64(-exponentDelta)), nil)
-		coefficient.Mul(coefficient, multiplier)
-	} else if exponentDelta > 0 {
-		divisor := new(apd.BigInt).Exp(apd.NewBigInt(10), apd.NewBigInt(int64(exponentDelta)), nil)
-		coefficient.Div(coefficient, divisor)
-	}
-
-	return &apd.Decimal{
-		Form:     decimal.Form,
-		Negative: decimal.Negative,
-		Exponent: newExponent,
-		Coeff:    *coefficient,
-	}
-}
-
 // encodeDecimalWithScale is used to encode a [*apd.Decimal] to `org.apache.kafka.connect.data.Decimal`
 // using a specific scale.
-func encodeDecimalWithScale(decimal *apd.Decimal, scale int32) []byte {
+func encodeDecimalWithScale(decimal *apd.Decimal, scale int32) ([]byte, error) {
 	targetExponent := -scale // Negate scale since [Decimal.Exponent] is negative.
 	if decimal.Exponent != targetExponent {
-		// TODO: We may be able to remove this conversion and just return an error to maintain parity with `org.apache.kafka.connect.data.Decimal`
+		// Return an error if the scales are different, this maintains parity with `org.apache.kafka.connect.data.Decimal`.
 		// https://github.com/a0x8o/kafka/blob/54eff6af115ee647f60129f2ce6a044cb17215d0/connect/api/src/main/java/org/apache/kafka/connect/data/Decimal.java#L69
-		slog.Warn("Value scale is different from schema scale",
-			slog.Any("value", decimal.Text('f')),
-			slog.Any("actual", -decimal.Exponent),
-			slog.Any("expected", scale),
-		)
-
-		decimal = decimalWithNewExponent(decimal, targetExponent)
+		return nil, fmt.Errorf("value scale (%d) is different from schema scale (%d)", -decimal.Exponent, scale)
 	}
 	bytes, _ := converters.EncodeDecimal(decimal)
-	return bytes
+	return bytes, nil
 }
 
 type decimalConverter struct {
@@ -93,7 +59,7 @@ func (d decimalConverter) Convert(value any) (any, error) {
 		return nil, fmt.Errorf(`unable to use %q as a decimal: %w`, stringValue, err)
 	}
 
-	return encodeDecimalWithScale(decimal, int32(d.scale)), nil
+	return encodeDecimalWithScale(decimal, int32(d.scale))
 }
 
 type VariableNumericConverter struct{}

lib/debezium/converters/decimal_test.go

@@ -9,36 +9,22 @@ import (
 	"github.com/artie-labs/transfer/lib/numbers"
 	"github.com/artie-labs/transfer/lib/ptr"
 	"github.com/artie-labs/transfer/lib/typing/decimal"
-	"github.com/cockroachdb/apd/v3"
 	"github.com/stretchr/testify/assert"
 )
 
-func TestDecimalWithNewExponent(t *testing.T) {
-	assert.Equal(t, "0", decimalWithNewExponent(apd.New(0, 0), 0).Text('f'))
-	assert.Equal(t, "00", decimalWithNewExponent(apd.New(0, 1), 1).Text('f'))
-	assert.Equal(t, "0", decimalWithNewExponent(apd.New(0, 100), 0).Text('f'))
-	assert.Equal(t, "00", decimalWithNewExponent(apd.New(0, 0), 1).Text('f'))
-	assert.Equal(t, "0.0", decimalWithNewExponent(apd.New(0, 0), -1).Text('f'))
-
-	// Same exponent:
-	assert.Equal(t, "12.349", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), -3).Text('f'))
-	// More precise exponent:
-	assert.Equal(t, "12.3490", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), -4).Text('f'))
-	assert.Equal(t, "12.34900", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), -5).Text('f'))
-	// Lest precise exponent:
-	// Extra digits should be truncated rather than rounded.
-	assert.Equal(t, "12.34", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), -2).Text('f'))
-	assert.Equal(t, "12.3", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), -1).Text('f'))
-	assert.Equal(t, "12", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), 0).Text('f'))
-	assert.Equal(t, "10", decimalWithNewExponent(numbers.MustParseDecimal("12.349"), 1).Text('f'))
-}
-
 func TestEncodeDecimalWithScale(t *testing.T) {
 	mustEncodeAndDecodeDecimal := func(value string, scale int32) string {
-		bytes := encodeDecimalWithScale(numbers.MustParseDecimal(value), scale)
+		bytes, err := encodeDecimalWithScale(numbers.MustParseDecimal(value), scale)
+		assert.NoError(t, err)
 		return converters.DecodeDecimal(bytes, scale).String()
 	}
 
+	mustReturnError := func(value string, scale int32) error {
+		_, err := encodeDecimalWithScale(numbers.MustParseDecimal(value), scale)
+		assert.Error(t, err)
+		return err
+	}
+
 	// Whole numbers:
 	for i := range 100_000 {
 		strValue := fmt.Sprint(i)
@@ -52,28 +38,10 @@ func TestEncodeDecimalWithScale(t *testing.T) {
 	// Scale of 15 that is equal to the amount of decimal places in the value:
 	assert.Equal(t, "145.183000000000000", mustEncodeAndDecodeDecimal("145.183000000000000", 15))
 	assert.Equal(t, "-145.183000000000000", mustEncodeAndDecodeDecimal("-145.183000000000000", 15))
-	// If scale is smaller than the amount of decimal places then the extra places should be truncated without rounding:
-	assert.Equal(t, "145.18300000000000", mustEncodeAndDecodeDecimal("145.183000000000000", 14))
-	assert.Equal(t, "145.18300000000000", mustEncodeAndDecodeDecimal("145.183000000000005", 14))
-	assert.Equal(t, "-145.18300000000000", mustEncodeAndDecodeDecimal("-145.183000000000005", 14))
-	assert.Equal(t, "145.18300000000000", mustEncodeAndDecodeDecimal("145.183000000000009", 14))
-	assert.Equal(t, "-145.18300000000000", mustEncodeAndDecodeDecimal("-145.183000000000009", 14))
-	assert.Equal(t, "-145.18300000000000", mustEncodeAndDecodeDecimal("-145.183000000000000", 14))
-	assert.Equal(t, "145.18300000000000", mustEncodeAndDecodeDecimal("145.183000000000001", 14))
-	assert.Equal(t, "-145.18300000000000", mustEncodeAndDecodeDecimal("-145.183000000000001", 14))
-	assert.Equal(t, "145.18300000000000", mustEncodeAndDecodeDecimal("145.183000000000004", 14))
-	assert.Equal(t, "-145.18300000000000", mustEncodeAndDecodeDecimal("-145.183000000000004", 14))
-	// If scale is larger than the amount of decimal places then the extra places should be padded with zeros:
-	assert.Equal(t, "145.1830000000000000", mustEncodeAndDecodeDecimal("145.183000000000000", 16))
-	assert.Equal(t, "-145.1830000000000000", mustEncodeAndDecodeDecimal("-145.183000000000000", 16))
-	assert.Equal(t, "145.1830000000000010", mustEncodeAndDecodeDecimal("145.183000000000001", 16))
-	assert.Equal(t, "-145.1830000000000010", mustEncodeAndDecodeDecimal("-145.183000000000001", 16))
-	assert.Equal(t, "145.1830000000000040", mustEncodeAndDecodeDecimal("145.183000000000004", 16))
-	assert.Equal(t, "-145.1830000000000040", mustEncodeAndDecodeDecimal("-145.183000000000004", 16))
-	assert.Equal(t, "145.1830000000000050", mustEncodeAndDecodeDecimal("145.183000000000005", 16))
-	assert.Equal(t, "-145.1830000000000050", mustEncodeAndDecodeDecimal("-145.183000000000005", 16))
-	assert.Equal(t, "145.1830000000000090", mustEncodeAndDecodeDecimal("145.183000000000009", 16))
-	assert.Equal(t, "-145.1830000000000090", mustEncodeAndDecodeDecimal("-145.183000000000009", 16))
+	// If scale is smaller than the amount of decimal places then an error should be returned:
+	assert.ErrorContains(t, mustReturnError("145.183000000000000", 14), "value scale (15) is different from schema scale (14)")
+	// If scale is larger than the amount of decimal places then an error should be returned:
+	assert.ErrorContains(t, mustReturnError("-145.183000000000005", 16), "value scale (15) is different from schema scale (16)")
 
 	assert.Equal(t, "-9063701308.217222135", mustEncodeAndDecodeDecimal("-9063701308.217222135", 9))
 	assert.Equal(t, "-74961544796695.89960242", mustEncodeAndDecodeDecimal("-74961544796695.89960242", 8))

lib/debezium/converters/money.go

@@ -56,5 +56,5 @@ func (m MoneyConverter) Convert(value any) (any, error) {
 		return nil, fmt.Errorf(`unable to use %q as a money value: %w`, valString, err)
 	}
 
-	return encodeDecimalWithScale(decimal, int32(m.Scale())), nil
+	return encodeDecimalWithScale(decimal, int32(m.Scale()))
 }