Michael Smith has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/21483 )

Change subject: IMPALA-12800: Use HashMap for ExprSubstitutionMap lookups
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Patch Set 4:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/21483/3/fe/src/main/java/org/apache/impala/analysis/ExprSubstitutionMap.java
File fe/src/main/java/org/apache/impala/analysis/ExprSubstitutionMap.java:

http://gerrit.cloudera.org:8080/#/c/21483/3/fe/src/main/java/org/apache/impala/analysis/ExprSubstitutionMap.java@49
PS3, Line 49:   // HashMap ourselves.
> Existing code manipulates LHS and RHS directly in a way that would be diffi
substituteLhs I think would be hard to match the performance of this 
implementation with LinkedHashMap because we would essentially need to recreate 
the HashMap and linked list of LinkedHashMap, where-as this implementation only 
needs to rebuild the HashMap. Admittedly I haven't tested the performance 
implications, but I think replacing with LinkedHashMap can be considered a 
separate refactoring that requires additive work.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ic538a82c69ee1dd76981fbacf95289c9d00ea9fe
Gerrit-Change-Number: 21483
Gerrit-PatchSet: 4
Gerrit-Owner: Michael Smith <[email protected]>
Gerrit-Reviewer: Daniel Becker <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Michael Smith <[email protected]>
Gerrit-Reviewer: Riza Suminto <[email protected]>
Gerrit-Comment-Date: Fri, 07 Jun 2024 20:39:52 +0000
Gerrit-HasComments: Yes

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