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From "Carl Steinbach (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-3289) sort merge join may not work silently
Date Tue, 31 Jul 2012 00:13:34 GMT

    [ https://issues.apache.org/jira/browse/HIVE-3289?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13425413#comment-13425413
] 

Carl Steinbach commented on HIVE-3289:
--------------------------------------

+1. Thanks for making these changes.

                
> sort merge join may not work silently
> -------------------------------------
>
>                 Key: HIVE-3289
>                 URL: https://issues.apache.org/jira/browse/HIVE-3289
>             Project: Hive
>          Issue Type: Bug
>          Components: Configuration, Query Processor
>            Reporter: Namit Jain
>            Assignee: Namit Jain
>         Attachments: hive.3289.1.patch
>
>
> The user does not know, if the sort-merge join is working or not.
> create table table_asc(key int, value string) CLUSTERED BY (key) SORTED BY (key asc)

> INTO 1 BUCKETS STORED AS RCFILE; 
> create table table_desc(key int, value string) CLUSTERED BY (key) SORTED BY (key desc)

> INTO 1 BUCKETS STORED AS RCFILE; 
> set hive.enforce.sorting = true;
> insert overwrite table table_asc select key, value from src;    
> insert overwrite table table_desc select key, value from src;
> set hive.optimize.bucketmapjoin = true;
> set hive.optimize.bucketmapjoin.sortedmerge = true;
> set hive.input.format = org.apache.hadoop.hive.ql.io.BucketizedHiveInputFormat;
> explain 
> select /*+mapjoin(a)*/ * from table_asc a join table_desc b on a.key = b.key;
> select /*+mapjoin(a)*/ * from table_asc a join table_desc b on a.key = b.key;
> explain
> select /*+mapjoin(b)*/ * from table_asc a join table_desc b on a.key = b.key;
> select /*+mapjoin(b)*/ * from table_asc a join table_desc b on a.key = b.key;
> In the above test, the sort-merge join is not obeyed as expected.
> If you user explicitly asked for sort-merge join, and it is not being
> obeyed, the operation should fail.

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