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https://issues.apache.org/jira/browse/HIVE-20220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16552433#comment-16552433
]
Hive QA commented on HIVE-20220:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
|| || || || {color:brown} Prechecks {color} ||
| {color:green}+1{color} | {color:green} @author {color} | {color:green} 0m
0s{color} | {color:green} The patch does not contain any @author tags. {color} |
|| || || || {color:brown} master Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 7m
48s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m
5s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m
40s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue} 3m
51s{color} | {color:blue} ql in master has 2280 extant Findbugs warnings.
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| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m
58s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 1m
26s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m
6s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 1m
6s{color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red} 0m
41s{color} | {color:red} ql: The patch generated 1 new + 55 unchanged - 0 fixed
= 56 total (was 55) {color} |
| {color:green}+1{color} | {color:green} whitespace {color} | {color:green} 0m
0s{color} | {color:green} The patch has no whitespace issues. {color} |
| {color:green}+1{color} | {color:green} findbugs {color} | {color:green} 4m
12s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m
59s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m
14s{color} | {color:green} The patch does not generate ASF License warnings.
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| {color:black}{color} | {color:black} {color} | {color:black} 23m 38s{color} |
{color:black} {color} |
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|| Subsystem || Report/Notes ||
| Optional Tests | asflicense javac javadoc findbugs checkstyle compile |
| uname | Linux hiveptest-server-upstream 3.16.0-4-amd64 #1 SMP Debian
3.16.36-1+deb8u1 (2016-09-03) x86_64 GNU/Linux |
| Build tool | maven |
| Personality |
/data/hiveptest/working/yetus_PreCommit-HIVE-Build-12788/dev-support/hive-personality.sh
|
| git revision | master / 170a012 |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.0 |
| checkstyle |
http://104.198.109.242/logs//PreCommit-HIVE-Build-12788/yetus/diff-checkstyle-ql.txt
|
| modules | C: ql U: ql |
| Console output |
http://104.198.109.242/logs//PreCommit-HIVE-Build-12788/yetus.txt |
| Powered by | Apache Yetus http://yetus.apache.org |
This message was automatically generated.
> Incorrect result when hive.groupby.skewindata is enabled
> --------------------------------------------------------
>
> Key: HIVE-20220
> URL: https://issues.apache.org/jira/browse/HIVE-20220
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Affects Versions: 3.0.0
> Reporter: Ganesha Shreedhara
> Assignee: Ganesha Shreedhara
> Priority: Major
> Attachments: HIVE-20220.patch
>
>
> hive.groupby.skewindata makes use of rand UDF to randomly distribute grouped
> by keys to the reducers and hence avoids overloading a single reducer when
> there is a skew in data.
> This random distribution of keys is buggy when the reducer fails to fetch the
> mapper output due to a faulty datanode or any other reason. When reducer
> finds that it can't fetch mapper output, it sends a signal to Application
> Master to reattempt the corresponding map task. The reattempted map task will
> now get the different random value from rand function and hence the keys that
> gets distributed now to the reducer will not be same as the previous run.
>
> *Steps to reproduce:*
> create table test(id int);
> insert into test values
> (1),(2),(2),(3),(3),(3),(4),(4),(4),(4),(5),(5),(5),(5),(5),(6),(6),(6),(6),(6),(6),(7),(7),(7),(7),(7),(7),(7),(7),(8),(8),(8),(8),(8),(8),(8),(8),(9),(9),(9),(9),(9),(9),(9),(9),(9);
> SET hive.groupby.skewindata=true;
> SET mapreduce.reduce.reduces=2;
> //Add a debug port for reducer
> select count(1) from test group by id;
> //Remove mapper's intermediate output file when map stage is completed and
> one out of 2 reduce tasks is completed and then continue the run. This causes
> 2nd reducer to send event to Application Master to rerun the map task.
> The following is the expected result.
> 1
> 2
> 3
> 4
> 5
> 6
> 8
> 8
> 9
>
> But you may get different result due to a different value returned by the
> rand function in the second run causing different distribution of keys.
> This needs to be fixed such that the mapper distributes the same keys even if
> it is reattempted multiple times.
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