[GitHub] [doris] englefly commented on a diff in pull request #11717: [fix](Nereids)memo copy in cannot rewrite current plan with its child

[GitBox <gi...@apache.org>]

englefly commented on code in PR #11717:
URL: https://github.com/apache/doris/pull/11717#discussion_r944146690


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fe/fe-core/src/main/java/org/apache/doris/nereids/memo/Memo.java:
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@@ -169,7 +169,8 @@ private Pair<Boolean, GroupExpression> rewriteGroupExpression(
             GroupExpression groupExpression, Group target, LogicalProperties logicalProperties) {
         boolean newGroupExpressionGenerated = true;
         GroupExpression existedGroupExpression = groupExpressions.get(groupExpression);
-        if (existedGroupExpression != null) {
+        if (existedGroupExpression != null
+                && (target == null || target.equals(existedGroupExpression.getOwnerGroup()))) {

Review Comment:
   if target is not null, and not the owner group of existedGroupExpression, should we merge them, as we do in insertGroupExpression()?
   Otherwise, there are two groups with equivalent group expressions in Memo.
   I think this issue is introduced by former pr, which split insertGroupExpression() and rewriteGroupExpression() from insertOrRewriteGroupExpression().



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