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From "Tim Armstrong (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-5483: Automatically disable codegen for small queries
Date Tue, 20 Jun 2017 20:52:52 GMT
Tim Armstrong has posted comments on this change.

Change subject: IMPALA-5483: Automatically disable codegen for small queries
......................................................................


Patch Set 3:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/7153/3//COMMIT_MSG
Commit Message:

PS3, Line 15: a plan node
> Is the 50K is corresponding to planner estimation. If yes, how about table 
MaxRowsProcessedVisitor detects when there are missing or corrupt stats and disabled the optimisation.

I agree there's an edge case where you have small input tables and an exploding many-to-many
join that the planner doesn't detect. In that case this could underestimate the number of
rows and disable codegen when it is better to enable it. I think we can live with that though
- it should be pretty rarer and there is always the safety valve of tweaking the query options.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I273bcee58641f5b97de52c0b2caab043c914b32e
Gerrit-PatchSet: 3
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Juan Yu <jyu@cloudera.com>
Gerrit-Reviewer: Michael Ho
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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