Daniel Becker has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/22407 )

Change subject: IMPALA-12588: Don't UPDATE rows that already have the desired 
value
......................................................................


Patch Set 2:

(8 comments)

http://gerrit.cloudera.org:8080/#/c/22407/2//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/22407/2//COMMIT_MSG@12
PS2, Line 12: them
Nit: line too long.


http://gerrit.cloudera.org:8080/#/c/22407/2//COMMIT_MSG@30
PS2, Line 30: where
I think we should capitalise it: "WHERE". Also the other instances where we 
refer to WHERE predicates or the statement.


http://gerrit.cloudera.org:8080/#/c/22407/2//COMMIT_MSG@49
PS2, Line 49: For some cases it can be trickier (e.g. UPDATE FROM), those cases
Could you include what happens with those cases after this patch? Do they 
remain as they were?


http://gerrit.cloudera.org:8080/#/c/22407/2/fe/src/main/java/org/apache/impala/analysis/UpdateStmt.java
File fe/src/main/java/org/apache/impala/analysis/UpdateStmt.java:

http://gerrit.cloudera.org:8080/#/c/22407/2/fe/src/main/java/org/apache/impala/analysis/UpdateStmt.java@54
PS2, Line 54: needsWherePredicateRewrite_
To me, this name suggests that there are cases where the WHERE predicate needs 
to be rewritten while in others it doesn't need to be.
I'd consider 'wherePredicateAlreadyRewritten' or 'wherePredicateRewriteDone'.


http://gerrit.cloudera.org:8080/#/c/22407/2/fe/src/main/java/org/apache/impala/analysis/UpdateStmt.java@141
PS2, Line 141: where
Capitalise WHERE.


http://gerrit.cloudera.org:8080/#/c/22407/2/fe/src/main/java/org/apache/impala/analysis/UpdateStmt.java@146
PS2, Line 146: 10
This could be extracted into a constant.


http://gerrit.cloudera.org:8080/#/c/22407/2/fe/src/main/java/org/apache/impala/analysis/UpdateStmt.java@149
PS2, Line 149: predicates
You could add more details to what the predicates are, especially as this tree 
is a bit different from the one in the commit message. There, 'a', 'b' and 'c' 
are the new values we're setting, and here they are the predicates 'col IS 
DISTINCT FROM value_a' etc.


http://gerrit.cloudera.org:8080/#/c/22407/2/testdata/workloads/functional-query/queries/QueryTest/iceberg-update-basic.test
File 
testdata/workloads/functional-query/queries/QueryTest/iceberg-update-basic.test:

http://gerrit.cloudera.org:8080/#/c/22407/2/testdata/workloads/functional-query/queries/QueryTest/iceberg-update-basic.test@332
PS2, Line 332: ref_view
Can we try add tests with the two other kinds of views: nested query and WITH 
statement views? In some places they are handled differently.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I926c80e8110de5a4615a3624a81a330f54317c8b
Gerrit-Change-Number: 22407
Gerrit-PatchSet: 2
Gerrit-Owner: Noemi Pap-Takacs <[email protected]>
Gerrit-Reviewer: Daniel Becker <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Noemi Pap-Takacs <[email protected]>
Gerrit-Reviewer: Peter Rozsa <[email protected]>
Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]>
Gerrit-Comment-Date: Wed, 12 Feb 2025 12:26:20 +0000
Gerrit-HasComments: Yes

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