Tim Armstrong has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/9005 )

Change subject: IMPALA-6314: Add run time scalar subquery check for 
uncorrelated subqueries
......................................................................


Patch Set 7:

(2 comments)

The backend code is looking good to me, comments are mainly about test 
coverage. I'm not confident about the frontend code, I'd like input from Alex 
or Dimitris about whether the approach is right.

http://gerrit.cloudera.org:8080/#/c/9005/6/be/src/exec/cardinality-check-node.cc
File be/src/exec/cardinality-check-node.cc:

http://gerrit.cloudera.org:8080/#/c/9005/6/be/src/exec/cardinality-check-node.cc@89
PS6, Line 89:     CopyRows
> No, in this case RowBatch::DeepCopyTo fails.
Yeah, I think we can just assume that the frontend will only generate plans 
with max_cardinality <= 1 for now and deal with additional complications later 
if we need the additional generality. We can't test the other cases now so 
seems best to be clear that it doesn't work.


http://gerrit.cloudera.org:8080/#/c/9005/7/be/src/exec/cardinality-check-node.cc
File be/src/exec/cardinality-check-node.cc:

http://gerrit.cloudera.org:8080/#/c/9005/7/be/src/exec/cardinality-check-node.cc@116
PS7, Line 116: Status CardinalityCheckNode::Reset(RuntimeState* state) {
I don't think we have test coverage for this code yet, since it's only executed 
if the node is inside a subplan. We do support this, e.g. the following query 
puts a cardinality check inside a subplan:

  select a.id from functional.allcomplextypes a
where id < (select item from a.int_array_col);

It looks like these planner tests and query tests have a number of subqueries 
that get put inside subplans:

  
./testdata/workloads/functional-planner/queries/PlannerTest/nested-collections.test
  
./testdata/workloads/functional-query/queries/QueryTest/nested-types-subplan.test

Your code does look like it handles subplans correctly, just want to make sure 
we have the test coverage.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I0f52b93a60eeacedd242a2f17fa6b99c4fc38e06
Gerrit-Change-Number: 9005
Gerrit-PatchSet: 7
Gerrit-Owner: Zoltan Borok-Nagy <[email protected]>
Gerrit-Reviewer: Attila Jeges <[email protected]>
Gerrit-Reviewer: Csaba Ringhofer <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Reviewer: Vuk Ercegovac <[email protected]>
Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]>
Gerrit-Comment-Date: Tue, 16 Jan 2018 21:54:33 +0000
Gerrit-HasComments: Yes

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