Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/819#discussion_r113606681
--- Diff: common/src/main/java/org/apache/drill/common/types/Types.java ---
@@ -636,43 +658,63 @@ public static String toString(final MajorType type) {
/**
* Get the <code>precision</code> of given type.
- * @param majorType
- * @return
+ *
+ * @param majorType major type
+ * @return precision value
*/
public static int getPrecision(MajorType majorType) {
- MinorType type = majorType.getMinorType();
-
- if (type == MinorType.VARBINARY || type == MinorType.VARCHAR) {
- return 65536;
- }
-
if (majorType.hasPrecision()) {
return majorType.getPrecision();
}
- return 0;
+ return isScalarStringType(majorType) ? MAX_VARCHAR_LENGTH : UNDEFINED;
}
/**
* Get the <code>scale</code> of given type.
- * @param majorType
- * @return
+ *
+ * @param majorType major type
+ * @return scale value
*/
public static int getScale(MajorType majorType) {
if (majorType.hasScale()) {
return majorType.getScale();
}
- return 0;
+ return UNDEFINED;
}
/**
- * Is the given type column be used in ORDER BY clause?
- * @param type
- * @return
+ * Checks if the given type column be used in ORDER BY clause.
+ *
+ * @param type minor type
+ * @return true if type can be used in ORDER BY clause
*/
public static boolean isSortable(MinorType type) {
// Currently only map and list columns are not sortable.
return type != MinorType.MAP && type != MinorType.LIST;
}
+
+ /**
+ * Sets max precision from both types if these types are string scalar
types.
+ * Sets max precision and scale from both types if these types are
decimal types.
+ *
+ * @param leftType type from left side
+ * @param rightType type from right side
+ * @param typeBuilder type builder
+ * @return type builder
+ */
+ public static MajorType.Builder calculateTypePrecisionAndScale(MajorType
leftType, MajorType rightType, MajorType.Builder typeBuilder) {
+ boolean isScalarString = Types.isScalarStringType(leftType) &&
Types.isScalarStringType(rightType);
+ boolean isDecimal = CoreDecimalUtility.isDecimalType(leftType);
+
+ if ((isScalarString || isDecimal) && 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()));
--- End diff --
Not sure this is right. From
[here](https://docs.microsoft.com/en-us/sql/t-sql/data-types/precision-scale-and-length-transact-sql):
"Precision is the number of digits in a number. Scale is the number of digits
to the right of the decimal point in a number. For example, the number 123.45
has a precision of 5 and a scale of 2."
So, if we have:
```
Decimal9(9,0)
Decimal9(9,9)
```
The result should be:
```
Decimal(18,9)
```
Or since this is out of range:
```
Decimal18(9,9)
```
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