yujun777 commented on code in PR #64335:
URL: https://github.com/apache/doris/pull/64335#discussion_r3503126282
##########
fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/SimplifyAggGroupBy.java:
##########
@@ -81,7 +81,56 @@ protected static boolean
isBinaryArithmeticSlot(TreeNode<Expression> expr) {
if (!supportedFunctions.contains(expr.getClass())) {
return false;
}
- return ExpressionUtils.isSlotOrCastOnSlot(expr.child(0)).isPresent()
&& expr.child(1) instanceof Literal
- ||
ExpressionUtils.isSlotOrCastOnSlot(expr.child(1)).isPresent() && expr.child(0)
instanceof Literal;
+
+ // Float/double arithmetic: precision loss for all operations
+ if (expr.child(0).getDataType().isFloatLikeType()
+ || expr.child(1).getDataType().isFloatLikeType()) {
+ return false;
+ }
+
+ Expression slotExpr;
+ Literal literal;
+ if (expr.child(0) instanceof Literal) {
+ literal = (Literal) expr.child(0);
+ slotExpr = expr.child(1);
+ } else if (expr.child(1) instanceof Literal) {
+ literal = (Literal) expr.child(1);
+ slotExpr = expr.child(0);
+ } else {
+ return false;
+ }
+
+ if (!canExtractSlot(slotExpr)) {
+ return false;
+ }
+
+ return checkLiteral(expr, literal);
}
+
+ @VisibleForTesting
+ protected static boolean checkLiteral(Expression expr, Literal literal) {
+ if (literal.isNullLiteral()) {
+ return false;
+ }
+ if (expr instanceof Multiply || expr instanceof Divide) {
Review Comment:
In SQL, division of two integers does not perform C-style truncating integer
division — the result type is promoted. For example, in Doris, `INT / INT`
promotes both operands to DOUBLE and returns a DOUBLE (see `TypePromotionMap`).
So `a=4` gives `2.0` and `a=5` gives `2.5` — different outputs for different
inputs. The division is injective.
The example `a/2` and `a/3` with `a=4` vs `a=5`:
- a=4: (2.0, 1.333...)
- a=5: (2.5, 1.666...)
These are distinct tuples, so simplifying `GROUP BY a/2, a/3` to `GROUP BY
a` is safe.
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