asolimando commented on code in PR #4557:
URL: https://github.com/apache/calcite/pull/4557#discussion_r2381676656
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core/src/main/java/org/apache/calcite/rex/RexUtil.java:
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@@ -1718,7 +1731,71 @@ public static boolean isLosslessCast(RelDataType source,
RelDataType target) {
final int targetPrecision = target.getPrecision();
return targetPrecision == PRECISION_NOT_SPECIFIED || targetPrecision >=
sourceLength;
}
- // Return FALSE by default
+
+ // 4) DECIMAL -> DECIMAL
+ if (sourceSqlTypeName == SqlTypeName.DECIMAL
+ && targetSqlTypeName == SqlTypeName.DECIMAL) {
+ int sourcePrecision = source.getPrecision();
+ int sourceScale = Math.max(source.getScale(), 0);
+ int targetPrecision = target.getPrecision();
+ int targetScale = Math.max(target.getScale(), 0);
+ if (sourcePrecision <= 0 || targetPrecision <= 0) {
+ return false;
+ }
+ return targetScale >= sourceScale
+ && (targetPrecision - targetScale) >= (sourcePrecision -
sourceScale);
+ }
+
+ // 5) integer family (signed or unsigned) -> DECIMAL
+ if (SqlTypeUtil.isIntType(source)
+ && targetSqlTypeName == SqlTypeName.DECIMAL) {
+ int targetPrecision = target.getPrecision();
+ int targetScale = Math.max(target.getScale(), 0);
+ int sourcePrecision = source.getPrecision();
+ if (sourcePrecision <= 0) {
Review Comment:
Not for the default type system, but I am being paranoid here in case people
mess things up with a custom type system and return `PRECISION_NOT_SPECIFIED`
somehow, but I agree it might be confusing as-is, I can either add a comment
specifying "this is not expected, just for extra safety" or even turn it into
an assert.
WDYT?
(there are other places where I have done that IIRC, I will adapt all places
when decided)
EDIT: I grep'ped the codebase to see if I could find such a handling for
integer precision, and I couldn't find any, so maybe I am overreacting here and
this check could be dropped entirely
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