silundong commented on code in PR #4459:
URL: https://github.com/apache/calcite/pull/4459#discussion_r2191548934
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core/src/main/java/org/apache/calcite/rel/metadata/RelMdDistinctRowCount.java:
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@@ -172,12 +172,18 @@ protected RelMdDistinctRowCount() {}
return 1D;
}
}
+ // the result of the aggregation function is difficult to infer, so if the
groupKey contains
+ // the aggregated column, return the full row count of Aggregate. This is
the most conservative
+ // estimate, and the actual ndv will not be greater than it.
+ if (groupKey.anyMatch(key -> key >= rel.getGroupCount())) {
Review Comment:
Here is to solve the issue mentioned in jira:
> when determining the pushable predicates, it makes the assumption that the
aggregate group key is a zero-based range, which is not necessarily the case
(the indices in the aggregate group key are the child indices, the predicates
are expressed in terms of the zero-based output range).
I have given an example in jira.
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