Jim Apple has posted comments on this change.

Change subject: IMPALA-4433: Fix undefined NDV calculations
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Patch Set 2:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/5004/1//COMMIT_MSG
Commit Message:

Line 10: argument is 0. This patch handles that 0 case, which can depend on the
> Might be good to mention that varies depending on the architecture.
Done


http://gerrit.cloudera.org:8080/#/c/5004/1/be/src/exprs/aggregate-functions-ir.cc
File be/src/exprs/aggregate-functions-ir.cc:

Line 1175:   // Use the lower bits to index into the number of streams and then 
find the first 1 bit
> Same comment as the other place - I think we can remove this branch.
Done


http://gerrit.cloudera.org:8080/#/c/5004/1/be/src/udf_samples/hyperloglog-uda.cc
File be/src/udf_samples/hyperloglog-uda.cc:

Line 75:   // Use the lower bits to index into the number of streams and then 
find the first 1 bit
> Let's remove this branch while we're at it. It doesn't make sense to me why
Done


PS1, Line 81:               (sizeof(hash_value) * CHAR_BIT - HLL_PRECISION));
            :   dst->ptr[idx] = ::max(dst->ptr[idx], first_one_bit);
> Can't we use the builtin you
It's in Impala proper, while it seems like the non-test files in this directory 
carefully avoid using anything from Impala proper.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I8460bc3f7e510ce07b8673387c9440accc432abe
Gerrit-PatchSet: 2
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Jim Apple <[email protected]>
Gerrit-Reviewer: Amos Bird <[email protected]>
Gerrit-Reviewer: Jim Apple <[email protected]>
Gerrit-Reviewer: Tim Armstrong <[email protected]>
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