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From "Tim Armstrong (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-3905: Add single-threaded scan node.
Date Thu, 25 Aug 2016 23:57:23 GMT
Tim Armstrong has posted comments on this change.

Change subject: IMPALA-3905: Add single-threaded scan node.
......................................................................


Patch Set 1:

(6 comments)

A few more comments. I think I understand the core of this a bit better - will wait for the
next patch now.

http://gerrit.cloudera.org:8080/#/c/4113/1/be/src/exec/hdfs-scan-node-mt.cc
File be/src/exec/hdfs-scan-node-mt.cc:

Line 57: 
We aren't accounting time in Open() in the same way we do in the non-mt scan node.


Line 61:   if (!initial_ranges_issued_) IssueInitialScanRanges(state);
Add a brief comment about why we don't do this in Open() - I see there's a similar comment
there.


Line 63:   if (ReachedLimit()) {
Is it a problem that we don't call StopAndFinalizeCounters() on this code path?


PS1, Line 81: reinterpret_cast
Not your change but I think these casts of meta_data() here and should probably be static_casts
instead because that's generally safe/more restrictive.

E.g. see https://www.securecoding.cert.org/confluence/display/cplusplus/EXP14-CPP.+Do+not+use+reinterpret_cast+on+pointers+to+class+objects+with+multiple+inheritence


http://gerrit.cloudera.org:8080/#/c/4113/1/be/src/exec/hdfs-scan-node.cc
File be/src/exec/hdfs-scan-node.cc:

Line 194:   SCOPED_TIMER(runtime_profile_->total_time_counter());
I guess we didn't track this before.


http://gerrit.cloudera.org:8080/#/c/4113/1/be/src/exec/hdfs-scan-node.h
File be/src/exec/hdfs-scan-node.h:

Line 60: /// An HdfsScanNode may expect to receive runtime filters produced elsewhere in the
plan
It seems like some of this comment (at least about the filters) should go into the base class.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I98cc7f970e1575dd83875609985e1877ada3d5e0
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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