mrhhsg commented on code in PR #64293:
URL: https://github.com/apache/doris/pull/64293#discussion_r3380822871
##########
fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/CountLiteralRewrite.java:
##########
@@ -107,10 +114,29 @@ private boolean isCountLiteral(AggregateFunction aggFunc)
{
&& aggFunc.child(0).isLiteral();
}
+ private boolean isCountConstantExpression(AggregateFunction aggFunc) {
+ if (aggFunc.isDistinct()
+ || !(aggFunc instanceof Count)
+ || aggFunc.children().size() != 1) {
+ return false;
+ }
+ Expression arg = aggFunc.child(0);
+ return !arg.isLiteral()
+ && arg.foldable()
+ && !arg.containsNondeterministic()
+ && !arg.containsVolatileExpression()
+ && arg.getInputSlots().isEmpty()
+ && !arg.containsType(AggregateFunction.class,
SubqueryExpr.class,
+ TableGeneratingFunction.class, WindowExpression.class);
+ }
+
private Expression rewrite(Count count) {
if (count.child(0).isNullLiteral()) {
return new BigIntLiteral(0);
Review Comment:
Thanks, addressed with a minimal targeted fix. I removed the broader
`isSafeToEvaluateAboveAggregate` direction and kept the normal count-constant
rewrite unchanged. For the empty-input case, `EliminateEmptyRelation` now
recognizes the `CountLiteralRewrite`-generated `if(arg is null, 0, count(*))`
projection above an empty aggregate and rewrites that result to literal `0`, so
the original count argument is no longer evaluated when there are no input rows.
I also added regression coverage for both sides:
- empty table + invalid JSON path returns `0`
- non-empty table + the same invalid JSON path still raises `Invalid Json
Path`
Validated with:
- `./run-fe-ut.sh --run
org.apache.doris.nereids.rules.rewrite.CountLiteralRewriteTest`
- `doris-local-regression ... all -d nereids_rules_p0/count_constant_rewrite
-s count_constant_rewrite -forceGenOut`
- `doris-local-regression ... all -d nereids_rules_p0/count_constant_rewrite
-s count_constant_rewrite`
- `git diff --check`
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