Alex Behm has posted comments on this change.

Change subject: IMPALA-3586: Implement union passthrough
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Patch Set 9:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/5816/9//COMMIT_MSG
Commit Message:

Line 15: as a precaution and for testing purposes.
> We made this decision with Alex in person a while ago. There are 2 reasons:
I agree that "blindly" adding query options is bad, but there are so many 
things that could go wrong this optimizations. There is the issue of 
tuple-layout compatibility and of memory management since we don't materialize 
any more. If there's a bug or a case we are missing or even a resource 
regression (e.g. increased memory consumption), then we have no resource 
without this query option.

The alternative is to test this to death until we are 100% confident there are 
no bugs. Still, there are cases where we know the passthrough might lead to a 
higher peak memory consumption.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ia8f6d5062724ba5b78174c3227a7a796d10d8416
Gerrit-PatchSet: 9
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Taras Bobrovytsky <[email protected]>
Gerrit-Reviewer: Alex Behm <[email protected]>
Gerrit-Reviewer: Dan Hecht <[email protected]>
Gerrit-Reviewer: Marcel Kornacker <[email protected]>
Gerrit-Reviewer: Taras Bobrovytsky <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
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