Quanlong Huang has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/24556 )

Change subject: IMPALA-15127: Support HBO for UnionNode cardinality
......................................................................


Patch Set 13:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/24556/8/fe/src/main/java/org/apache/impala/planner/UnionNode.java
File fe/src/main/java/org/apache/impala/planner/UnionNode.java:

http://gerrit.cloudera.org:8080/#/c/24556/8/fe/src/main/java/org/apache/impala/planner/UnionNode.java@376
PS8, Line 376:     if (!constExprLists_.isEmpty()) {
> Ack
PS13 addes the constants into the key.


http://gerrit.cloudera.org:8080/#/c/24556/8/fe/src/main/java/org/apache/impala/planner/UnionNode.java@415
PS8, Line 415:     }
> PS12 still leaves a no-scan path through a parent node. `select 1 union sel
Extended the code to allow empty scan input stats for matching const-only 
UnionNodes. Also added the constants into the HBO key string so the matching 
ensures constants are identical. Note that we don't want to track const-only 
UnionNodes since their cardinalities are clear and accurate. However, for 
ancestor nodes of const-only UnionNodes, planner can only estimate the 
cardinality so we track them in HBO.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ie228f530bdcb171d3b717966673164bf9a4c45c8
Gerrit-Change-Number: 24556
Gerrit-PatchSet: 13
Gerrit-Owner: Quanlong Huang <[email protected]>
Gerrit-Reviewer: Aleksandr Efimov <[email protected]>
Gerrit-Reviewer: Aman Sinha <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Quanlong Huang <[email protected]>
Gerrit-Reviewer: Steve Carlin <[email protected]>
Gerrit-Comment-Date: Fri, 14 Aug 2026 05:48:08 +0000
Gerrit-HasComments: Yes

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