Tim Armstrong has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/13807 )

Change subject: IMPALA-8741: Speed up bit unpacking by vectorisation
......................................................................


Patch Set 15:

(2 comments)

Thanks for the fixes. I think I'm going to struggle to find time to review the 
core unpacking logic. Csaba, are you planning to review that?

http://gerrit.cloudera.org:8080/#/c/13807/4/be/src/util/bit-packing.h
File be/src/util/bit-packing.h:

http://gerrit.cloudera.org:8080/#/c/13807/4/be/src/util/bit-packing.h@67
PS4, Line 67:   template <typename OutType>
> Csaba had an idea that we could get rid of the VECTORIZE parameter complete
Ah if there is a measurable difference then the template parameter is OK by me, 
I just thought it might be fair enough outside the hot loops that it didn't 
make a difference. Either way it's a good improvement!


http://gerrit.cloudera.org:8080/#/c/13807/4/be/src/util/bit-packing.inline.h
File be/src/util/bit-packing.inline.h:

http://gerrit.cloudera.org:8080/#/c/13807/4/be/src/util/bit-packing.inline.h@84
PS4, Line 84:   if (LIKELY((std::is_same<OutType, uint8_t>::value
> We also use bool somewhere, at least bit-packing.cc instantiates the method
Probably ParquetBoolDecoder::DecodeValue(). Might be worth seeing if you can 
switch that to storing an array of uint8_t and remove this.

I think supporting signed values in these low-level routines is probably adding 
unnecessary complexity.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I9e452a547973778bbd8d768c608e1a32e948f947
Gerrit-Change-Number: 13807
Gerrit-PatchSet: 15
Gerrit-Owner: Daniel Becker <[email protected]>
Gerrit-Reviewer: Csaba Ringhofer <[email protected]>
Gerrit-Reviewer: Daniel Becker <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
Gerrit-Comment-Date: Wed, 24 Jul 2019 00:53:10 +0000
Gerrit-HasComments: Yes

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