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From "Tim Armstrong (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4654: KuduScanner must return when ReachedLimit()
Date Wed, 14 Dec 2016 15:59:34 GMT
Tim Armstrong has posted comments on this change.

Change subject: IMPALA-4654: KuduScanner must return when ReachedLimit()
......................................................................


Patch Set 2: Code-Review+1

(1 comment)

http://gerrit.cloudera.org:8080/#/c/5493/2/be/src/exec/kudu-scanner.cc
File be/src/exec/kudu-scanner.cc:

PS2, Line 200: scan_node_->ReachedLimit()
> Yeah this is a good point, I'll file a separate JIRA for us to address how 
Agree we should fix it.

I think we won't run into any (serious) problems in practice, since there's a memory barrier
when we acquire the queue locks to add each batch.

The once-per-row check here may not behave as expected since it could be cached. In the HDFS
scanners I believe it's only checked once per batch anyway. The scan node needs to truncate
the batches correctly regardless. 

I don't think we need to check this every row for Kudu, so we should consider changing it.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Iaddd51111a1b2647995d68e6d37d0500b3a322de
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Matthew Jacobs <mj@cloudera.com>
Gerrit-Reviewer: Sailesh Mukil <sailesh@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Todd Lipcon <todd@apache.org>
Gerrit-HasComments: Yes

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