Csaba Ringhofer has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/22738 )

Change subject: IMPALA-915: Cancel catalog ops for queries
......................................................................


Patch Set 15:

(2 comments)

http://gerrit.cloudera.org:8080/#/c/22738/12//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/22738/12//COMMIT_MSG@7
PS12, Line 7: queries
Can you add details about what queries are affected? The tests I see are about 
REFRESH / any query that leads to loading the tables. Are DDLs/DMLs also 
affected?


http://gerrit.cloudera.org:8080/#/c/22738/12//COMMIT_MSG@9
PS12, Line 9: Adds support to cancel metadata operations with catalogd by 
sending a
            : Cancel request to catalogd for the relevant query ID. Registers 
Java
            : Threads executing select catalog operations by their query ID.
> Just FYI, canceling global "INVALIDATE METADATA" query might be trickier af
I am unsure about the high level design - isn't it enough to make the 
coordinator side interruptible with cancel and let the catalogd finish what it 
was asked to do?

In the case when the table is not yet loaded and the FE is blocked waiting for 
the catalog to load the table, it is not clear to me that we win with 
cancelling table loading in the catalog - the table is likely to be somewhat 
"hot", so another query is likely to load it anyway, and we lose the progress 
made by the cancelled query. It seems better to me to finish loading and return 
the results to the coordinator cache (and in parallel unblock the FE thread to 
not wait for it).



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Iab22855bd2d63b64da008b52aa33230a6f422537
Gerrit-Change-Number: 22738
Gerrit-PatchSet: 15
Gerrit-Owner: Michael Smith <[email protected]>
Gerrit-Reviewer: Csaba Ringhofer <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Jason Fehr <[email protected]>
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Michael Smith <[email protected]>
Gerrit-Reviewer: Quanlong Huang <[email protected]>
Gerrit-Reviewer: Riza Suminto <[email protected]>
Gerrit-Comment-Date: Sun, 13 Jul 2025 13:30:48 +0000
Gerrit-HasComments: Yes

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