hive-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Yongzhi Chen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-11502) Map side aggregation is extremely slow
Date Fri, 14 Aug 2015 11:48:45 GMT

    [ https://issues.apache.org/jira/browse/HIVE-11502?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14696920#comment-14696920
] 

Yongzhi Chen commented on HIVE-11502:
-------------------------------------

The TestDummy failure is not related:

It failed because of FileNotFoundException:    
[exec] + javac -cp /home/hiveptest/54.147.251.176-hiveptest-2/maven/org/apache/hive/hive-exec/2.0.0-SNAPSHOT/hive-exec-2.0.0-SNAPSHOT.jar
/tmp/UDFExampleAdd.java -d /tmp
     [exec] + jar -cf /tmp/udfexampleadd-1.0.jar -C /tmp UDFExampleAdd.class
     [exec] java.io.FileNotFoundException: /tmp/UDFExampleAdd.class (No such file or directory)
     [exec] 	at java.io.FileInputStream.open(Native Method)
     [exec] 	at java.io.FileInputStream.<init>(FileInputStream.java:146)
     [exec] 	at sun.tools.jar.Main.copy(Main.java:791)
     [exec] 	at sun.tools.jar.Main.addFile(Main.java:740)
     [exec] 	at sun.tools.jar.Main.create(Main.java:491)
     [exec] 	at sun.tools.jar.Main.run(Main.java:201)
     [exec] 	at sun.tools.jar.Main.main(Main.java:1177)


> Map side aggregation is extremely slow
> --------------------------------------
>
>                 Key: HIVE-11502
>                 URL: https://issues.apache.org/jira/browse/HIVE-11502
>             Project: Hive
>          Issue Type: Bug
>          Components: Logical Optimizer, Physical Optimizer
>    Affects Versions: 1.2.0
>            Reporter: Yongzhi Chen
>            Assignee: Yongzhi Chen
>         Attachments: HIVE-11502.1.patch, HIVE-11502.2.patch
>
>
> For the query as following:
> {noformat}
> create table tbl2 as 
> select col1, max(col2) as col2 
> from tbl1 group by col1;
> {noformat}
> If the column for group by has many different values (for example 400000) and it is in
type double, the map side aggregation is very slow. I ran the query which took more than 3
hours , after 3 hours, I have to kill the query.
> The same query can finish in 7 seconds, if I turn off map side aggregation by:
> {noformat}
> set hive.map.aggr = false;
> {noformat}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message