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From "Taras Bobrovytsky (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4939, IMPALA-4939: Decimal V2 multiplication
Date Sat, 29 Jul 2017 01:38:28 GMT
Taras Bobrovytsky has posted comments on this change.

Change subject: IMPALA-4939, IMPALA-4939: Decimal V2 multiplication
......................................................................


Patch Set 3:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/7438/1/be/src/runtime/decimal-value.inline.h
File be/src/runtime/decimal-value.inline.h:

Line 301:       // doubling such a value would overflow in two's complement.  However, we
> A while loop will perform terribly, but there are intrinsics that can be us
Added a TODO.


http://gerrit.cloudera.org:8080/#/c/7438/1/be/src/util/bit-util.h
File be/src/util/bit-util.h:

Line 65:     return value < 0 ? -1 : 1;
> I think we want to think carefully about using the Sign function with int25
I included the benchmark result in the commit message.


http://gerrit.cloudera.org:8080/#/c/7438/1/be/src/util/decimal-util.h
File be/src/util/decimal-util.h:

Line 336
> Really?  That's crazy.
I removed this function so that the function on line 58 would get called.


http://gerrit.cloudera.org:8080/#/c/7438/1/fe/src/main/java/org/apache/impala/analysis/TypesUtil.java
File fe/src/main/java/org/apache/impala/analysis/TypesUtil.java:

Line 260:         resultPrecision = p1 + p2 + 1;
> I think the 0.999 * 0.999 case is a fluke - we are sacrificing precision fo
This is more of a product question. I'll ask Greg about this later.


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Gerrit-MessageType: comment
Gerrit-Change-Id: I37ad6232d7953bd75c18dc86e665b2b501a1ebe1
Gerrit-PatchSet: 3
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Taras Bobrovytsky <tbobrovytsky@cloudera.com>
Gerrit-Reviewer: Dan Hecht <dhecht@cloudera.com>
Gerrit-Reviewer: Michael Ho <kwho@cloudera.com>
Gerrit-Reviewer: Taras Bobrovytsky <tbobrovytsky@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: Zach Amsden <zamsden@cloudera.com>
Gerrit-HasComments: Yes

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