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https://issues.apache.org/jira/browse/HIVE-23356?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17098003#comment-17098003
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Hive QA commented on HIVE-23356:
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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} 9m
49s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 0m
58s{color} | {color:green} master passed {color} |
| {color:green}+1{color} | {color:green} checkstyle {color} | {color:green} 0m
41s{color} | {color:green} master passed {color} |
| {color:blue}0{color} | {color:blue} findbugs {color} | {color:blue} 3m
37s{color} | {color:blue} ql in master has 1530 extant Findbugs warnings.
{color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m
55s{color} | {color:green} master passed {color} |
|| || || || {color:brown} Patch Compile Tests {color} ||
| {color:green}+1{color} | {color:green} mvninstall {color} | {color:green} 1m
25s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} compile {color} | {color:green} 1m
1s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javac {color} | {color:green} 1m
1s{color} | {color:green} the patch passed {color} |
| {color:red}-1{color} | {color:red} checkstyle {color} | {color:red} 0m
38s{color} | {color:red} ql: The patch generated 2 new + 24 unchanged - 0 fixed
= 26 total (was 24) {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} 3m
51s{color} | {color:green} the patch passed {color} |
| {color:green}+1{color} | {color:green} javadoc {color} | {color:green} 0m
53s{color} | {color:green} the patch passed {color} |
|| || || || {color:brown} Other Tests {color} ||
| {color:green}+1{color} | {color:green} asflicense {color} | {color:green} 0m
15s{color} | {color:green} The patch does not generate ASF License warnings.
{color} |
| {color:black}{color} | {color:black} {color} | {color:black} 24m 40s{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
3.16.43-2+deb8u5 (2017-09-19) x86_64 GNU/Linux |
| Build tool | maven |
| Personality |
/data/hiveptest/working/yetus_PreCommit-HIVE-Build-22080/dev-support/hive-personality.sh
|
| git revision | master / 1f527fd |
| Default Java | 1.8.0_111 |
| findbugs | v3.0.1 |
| checkstyle |
http://104.198.109.242/logs//PreCommit-HIVE-Build-22080/yetus/diff-checkstyle-ql.txt
|
| modules | C: ql U: ql |
| Console output |
http://104.198.109.242/logs//PreCommit-HIVE-Build-22080/yetus.txt |
| Powered by | Apache Yetus http://yetus.apache.org |
This message was automatically generated.
> Hash aggregation is always disabled while processing querys with grouping
> sets expressions.
> -------------------------------------------------------------------------------------------
>
> Key: HIVE-23356
> URL: https://issues.apache.org/jira/browse/HIVE-23356
> Project: Hive
> Issue Type: Bug
> Components: Hive, Operators, Query Processor
> Affects Versions: All Versions
> Reporter: Qiang.Kang
> Assignee: Qiang.Kang
> Priority: Critical
> Labels: performance
> Attachments: HIVE-23356.01.patch, HIVE-23356.02.patch,
> HIVE-23356.03.patch
>
>
> Hi, we find that many MapReduce map attempts disable hash aggregation while
> processing GroupBy Operator with grouping sets expressions. Logs are just
> like this:
> `Disable Hash Aggr: #hash table = 104427 #total = 100000 reduction = 1.0
> minReduction = 0.5`, which means hashTable size is even larger than the
> number of input rows.
> Dig deeper we can find that GroupBy operator disables hash aggregation just
> based on the number of input rows instead of rows actually processed. For
> GroupBy Operator with grouping sets (such as: roll up, cube, etc.),
> `numberRowsProcessed` equals `groupingSets.size()*numberRowsInput`, causing
> hashTableSize much larger than querys without grouping sets expressions.
> Let's consider a example below:
> - Query:
> SELECT col1, col2, MAX(col0) FROM tbl GROUP BY col1, col2 GROUPING SETS
> (col1,col2);
> - Input data:
> col0, col1, col2
> [0,-1,-1]
> [1,-1,-1]
> [2,-1,-1]
> [3,3,3]
> [4,4,4]
> - Configuration:
> hive.groupby.mapaggr.checkinterval = 1;
> minReductionHashAggr = 0.5;
> - Currently, there are 10 rows in partial aggregate result. (hash aggregation
> is disabled very early):
> [-1, null, 0]
> [null, -1, 0]
> [-1, null, 1]
> [null, -1, 1]
> [-1, null, 2]
> [null, -1, 2]
> [3, null, 3]
> [null, 3, 3]
> [4, null, 4]
> [null, 4, 4]
> The patch below disables hash aggregation based on the number of rows
> actually processed, reducing partial result entries a lot and improving the
> performance of aggregation. There are only 6 rows in partial aggregate result:
> [-1, null, 2]
> [null, -1, 2]
> [null, 3, 3]
> [4, null, 4]
> [null, 4, 4]
> [3, null, 3]
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