paul-rogers commented on a change in pull request #2006: DRILL-7615: UNION ALL
query returns the wrong result for the decimal value
URL: https://github.com/apache/drill/pull/2006#discussion_r386776641
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File path: common/src/main/java/org/apache/drill/common/types/Types.java
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@@ -795,15 +807,25 @@ public static boolean isSortable(MinorType type) {
*/
public static MajorType.Builder calculateTypePrecisionAndScale(MajorType
leftType, MajorType rightType, MajorType.Builder typeBuilder) {
if (leftType.getMinorType().equals(rightType.getMinorType())) {
- final boolean isScalarString = Types.isScalarStringType(leftType) &&
Types.isScalarStringType(rightType);
- final boolean isDecimal = isDecimalType(leftType);
+ boolean isScalarString = Types.isScalarStringType(leftType) &&
Types.isScalarStringType(rightType);
+ boolean isDecimal = isDecimalType(leftType);
- if ((isScalarString || isDecimal) && leftType.hasPrecision() &&
rightType.hasPrecision()) {
+ if (isScalarString && leftType.hasPrecision() &&
rightType.hasPrecision()) {
typeBuilder.setPrecision(Math.max(leftType.getPrecision(),
rightType.getPrecision()));
}
- if (isDecimal && leftType.hasScale() && rightType.hasScale()) {
- typeBuilder.setScale(Math.max(leftType.getScale(),
rightType.getScale()));
+ if (isDecimal) {
+ int scale = Math.max(leftType.getScale(), rightType.getScale());
+ // resulting precision should take into account resulting scale value
and be calculated as
+ // sum of two components:
+ // - max integer digits number (precision - scale) for left and right;
+ // - resulting scale.
+ // So for the case of cast(9999 as decimal(4,0)) and cast(1.23 as
decimal(3,2))
+ // resulting scale would be Max(0, 2) = 2 and resulting precision
would be Max(4 - 0, 3 - 2) + 2 = 6.
+ // In this case, both values would fit into decimal(6, 2): 9999.00,
1.23
+ int precision = Math.max(leftType.getPrecision() -
leftType.getScale(), rightType.getPrecision() - rightType.getScale()) + scale;
+ typeBuilder.setPrecision(precision);
+ typeBuilder.setScale(scale);
Review comment:
Nit: please split the long line.
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