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From "Bharath Vissapragada (Code Review)" <>
Subject [Impala-CR](cdh5-trunk) IMPALA-3680: Reset the file read offset for failed hdfs cache reads
Date Thu, 09 Jun 2016 12:34:44 GMT
Bharath Vissapragada has posted comments on this change.

Change subject: IMPALA-3680: Reset the file read offset for failed hdfs cache reads

Patch Set 2:

Commit Message:

PS1, Line 12: re-issuing the whole set of scan ranges
> Thanks.  Can you incorporate this in the commit message or JIRA?

Line 23: sped up with performance close to non-cached query runs.
> I think we need a way to exercise this path in testing.  For instance, the 
I think we can use IMPALA-3679 for this, where ZCRs are known to fail with caching in encryption
zones. I wrote a simple test for this, let me know if you think its ok.
File be/src/runtime/

Line 432:       hdfsSeek(fs_, hdfs_file_->file(), offset_);
> Regarding Open(), I was wondering why the call to Open() in DiskIoMgr::Read
I didn't call Close() initially as it is heavier than hdfsSeek() but yea I agree with your
point that it should undo all the side effects of Open(). Changed it now.

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Gerrit-MessageType: comment
Gerrit-Change-Id: I0a9ea19dd8571b01d2cd5b87da1c259219f6297a
Gerrit-PatchSet: 2
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Bharath Vissapragada <>
Gerrit-Reviewer: Bharath Vissapragada <>
Gerrit-Reviewer: Dan Hecht <>
Gerrit-HasComments: Yes

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