Bankim Bhavsar has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/15600 )

Change subject: [util] Add special handling for nullptr in fast hash
......................................................................


Patch Set 1:

(4 comments)

http://gerrit.cloudera.org:8080/#/c/15600/1//COMMIT_MSG
Commit Message:

http://gerrit.cloudera.org:8080/#/c/15600/1//COMMIT_MSG@20
PS1, Line 20: compatibilty
> compatibility
Done


http://gerrit.cloudera.org:8080/#/c/15600/1/java/kudu-client/src/main/java/org/apache/kudu/util/HashUtil.java
File java/kudu-client/src/main/java/org/apache/kudu/util/HashUtil.java:

http://gerrit.cloudera.org:8080/#/c/15600/1/java/kudu-client/src/main/java/org/apache/kudu/util/HashUtil.java@a92
PS1, Line 92:
> Perhaps the intent was to allow computing the hash on a slice of the array
That wasn't the intent. Had that been the case, there would have been 
validation "len <= buf.length" which is missing.


http://gerrit.cloudera.org:8080/#/c/15600/1/java/kudu-client/src/main/java/org/apache/kudu/util/HashUtil.java@24
PS1, Line 24:   // Constant imported from Apache Impala used to compute hash 
values for special cases.
            :   // Constant obtained by taking lower bytes of generated UUID.
> 1. What's the "generated UUID" you're alluding to?
This is the UUID that was once generated in Impala. 2nd line taken straight 
from Impala source. 1st line mentions about the import from Impala.

> 2. Is it important that this value matches the value in Apache Impala? If so, 
> why?
Yes.
Impala will use the direct BlockBloomFilter API and insert hash value directly 
using it's own existing implementation of the fast hash. Hence the value must 
match with Impala.
https://github.com/apache/impala/blob/master/be/src/runtime/raw-value-ir.cc#L179


http://gerrit.cloudera.org:8080/#/c/15600/1/src/kudu/util/hash_util.h
File src/kudu/util/hash_util.h:

http://gerrit.cloudera.org:8080/#/c/15600/1/src/kudu/util/hash_util.h@32
PS1, Line 32: // Constant imported from Apache Impala used to compute hash 
values for special cases.
> If you end up changing the comment in the Java code to reflect my questions
Ack



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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Idf1ccff3dde7ccf54c4c2c6c2910915c69153316
Gerrit-Change-Number: 15600
Gerrit-PatchSet: 1
Gerrit-Owner: Bankim Bhavsar <[email protected]>
Gerrit-Reviewer: Adar Dembo <[email protected]>
Gerrit-Reviewer: Bankim Bhavsar <[email protected]>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Wenzhe Zhou <[email protected]>
Gerrit-Comment-Date: Mon, 30 Mar 2020 22:41:17 +0000
Gerrit-HasComments: Yes

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