Qifan Chen has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/16719 )

Change subject: IMPALA-10323: use snprintf instead of lexical_cast to cast to 
string
......................................................................


Patch Set 1:

(1 comment)

I like the idea of pushing for more performance for Impala and agree with other 
reviewers to show the improvement in the commit message.

It may be useful to test the raw performance of both the old and new version of 
CAST_TO_STRING() in isolated testing code, say in a 1000- iteration loop.

http://gerrit.cloudera.org:8080/#/c/16719/1/be/src/exprs/cast-functions-ir.cc
File be/src/exprs/cast-functions-ir.cc:

http://gerrit.cloudera.org:8080/#/c/16719/1/be/src/exprs/cast-functions-ir.cc@137
PS1, Line 137: if (std::isnan(val.val)) return StringVal("nan"); \
I wonder if there is a need to test nan here when num_type is neither float or 
double. Suggest to have two versions of code, one for exact numeric, and one 
for approximate numeric.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ief1d6b2c2cb5961c1d6cee1b0eac86ab61509768
Gerrit-Change-Number: 16719
Gerrit-PatchSet: 1
Gerrit-Owner: wesleydeng <[email protected]>
Gerrit-Reviewer: Csaba Ringhofer <[email protected]>
Gerrit-Reviewer: Gabor Kaszab <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Qifan Chen <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Reviewer: abeltian <[email protected]>
Gerrit-Reviewer: wesleydeng <[email protected]>
Gerrit-Comment-Date: Tue, 17 Nov 2020 15:50:55 +0000
Gerrit-HasComments: Yes

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