Attila Jeges has posted comments on this change.

Change subject: IMPALA-1731,IMPALA-3868: Float values are not parsed correctly
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Patch Set 4:

(4 comments)

There is a benchmark program (atof-benchmark) to test the performance of 
StringToFloat. 

The performance degraded a bit. Before applying the change the number of 
iterations per millisecond was about 11.2, after the change it is 8.33. 
StringToFloat still performs better than atof though. atof does 5.19 iterations 
per millisecond.

http://gerrit.cloudera.org:8080/#/c/3622/4//COMMIT_MSG
Commit Message:

PS4, Line 7: MPALA
> IMPALA
Done


PS4, Line 12: Trailing
> leading too
Actually, StringParser class has two static functions that deal with  float 
parsing: StringToFloat and StringToFloatInternal. StringToFloat is public, 
StringToFloatInternal is private.

StringToFloatInternal is merely a helper function to StringToFloat. 
StringToFloat skips leading whitespace and then simply calls 
StringToFloatInternal. Thus, StringToFloat accepts leading whitespace while 
StringToFloatInternal does not. The commit message talks only about 
StringToFloatInternal.

Since StringToFloatInternal is private, we cannot test it directly. We can only 
test StringToFloat, but then we have to test that it works with leading 
whitespace as well.


PS4, Line 12: strings like
> remove "strings like". These are the only strings.
Done


PS4, Line 16: Trailing
> leading too
Same as above.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I9e17d0f051b300a22a520ce34e276c2d4460d35e
Gerrit-PatchSet: 4
Gerrit-Project: Impala
Gerrit-Branch: cdh5-trunk
Gerrit-Owner: Attila Jeges <[email protected]>
Gerrit-Reviewer: Attila Jeges <[email protected]>
Gerrit-Reviewer: Jim Apple <[email protected]>
Gerrit-Reviewer: Lars Volker <[email protected]>
Gerrit-Reviewer: Matthew Jacobs <[email protected]>
Gerrit-Reviewer: Michael Ho <[email protected]>
Gerrit-HasComments: Yes

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