Tim Armstrong has posted comments on this change.

Change subject: IMPALA-4883: Implement Codegen for Union
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Patch Set 2:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/6459/2/be/src/exec/union-node.cc
File be/src/exec/union-node.cc:

Line 184:   if (UNLIKELY(codegend_union_materialize_exprs_fns_.size() == 0 ||
> It would be great if we could avoid all of this per-row overhead - I'm coun
Just to confirm my suspicion, it would be good to run "perf top" while your 
benchmark is running. My guess is that it will spend a lot of time in 
MaterializeExprs()/GetNextMaterialized() . Ideally when we codegen something it 
should spend almost all of the time in the codegen'd code.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ib4107d27582ff5416172810364a6e76d3d93c439
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Taras Bobrovytsky <[email protected]>
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-Reviewer: Taras Bobrovytsky <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-HasComments: Yes

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