mihaibudiu commented on code in PR #3860:
URL: https://github.com/apache/calcite/pull/3860#discussion_r1679687994
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core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java:
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@@ -988,15 +988,15 @@ void propagateCostImprovements(RelNode rel) {
continue;
}
- // Update the RelNode's cost when we find that the cost is changed.
- //
- // Why do we need to update it?
- // When RelSet's one of the subsets find a cheaper RelNode, we need to
update the
- // parents of the subset to have the best RelNode and best cost.
- // In theory, this cost will become smaller, But according to
- // the SQL we added in the JdbcAdapterTest {@link
testVolcanoPlannerInternalValid},
- // it shows RelNode's cost will become bigger sometimes.
- // So we update it.
+ // The cost of the RelNode is updated when a change is detected.
Review Comment:
This looks good. If the original author can confirm that this is that the
rewrites convey his intention, we can merge it.
I am not sure about the commit message, because I don't know what "strong"
is.
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