morrySnow commented on code in PR #67878:
URL: https://github.com/apache/doris/pull/67878#discussion_r4034599975
##########
fe/fe-core/src/main/java/org/apache/doris/nereids/util/ExpressionUtils.java:
##########
@@ -1205,9 +1205,63 @@ public static boolean isInjective(Expression expression)
{
return expression instanceof Slot;
}
- // if the input is unique, the output of agg is unique, too
+ private static boolean isInjectiveAggArgument(Expression expression) {
+ if (expression instanceof Slot) {
+ return true;
+ }
+ if (!(expression instanceof Cast)) {
+ return false;
+ }
+ Cast cast = (Cast) expression;
+ DataType source = cast.child().getDataType();
+ DataType target = cast.getDataType();
+ // Bounded character casts may truncate to the declared length. Treat
every non-identity
+ // conversion to CHAR/VARCHAR conservatively, including
analyzer-generated casts.
+ return (source.equals(target) || (!target.isCharType() &&
!target.isVarcharType()))
+ && !Cast.castNullable(false, source, target)
+ && isInjectiveTypeConversion(source, target)
+ && isInjectiveAggArgument(cast.child());
+ }
+
+ /**
+ * Whether an aggregate preserves uniqueness for a group containing
exactly one row.
+ *
+ * <p>Checking the aggregate kind and its input slots is not sufficient.
An aggregate argument
+ * may contain a non-injective expression, and the aggregate return type
may also collapse
+ * distinct argument values. Prove injectivity through both the argument
expression and the
+ * one-row argument-to-result type conversion.
+ */
public static boolean isInjectiveAgg(Expression agg) {
- return agg instanceof Sum || agg instanceof Avg || agg instanceof Max
|| agg instanceof Min;
+ if (!(agg instanceof Sum || agg instanceof Avg || agg instanceof Max
|| agg instanceof Min)) {
+ return false;
+ }
+ Expression argument = agg.child(0);
+ return isInjectiveAggArgument(argument)
+ && isInjectiveTypeConversion(argument.getDataType(),
agg.getDataType());
+ }
+
+ /**
+ * Whether a type conversion preserves every source value. Data types
provide the general
+ * proof; the floating-point cases below supplement it with the exact
integer ranges of IEEE
+ * 754 binary32 and binary64.
+ */
+ private static boolean isInjectiveTypeConversion(DataType source, DataType
target) {
+ if (source.isInjectiveCastTo(target)) {
+ return true;
+ }
+ if (source.isIntegralType()) {
Review Comment:
decimalv2 is deperated
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