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From "Navis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6099) Multi insert does not work properly with distinct count
Date Mon, 11 Aug 2014 07:15:12 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6099?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14092516#comment-14092516
] 

Navis commented on HIVE-6099:
-----------------------------

[~leftylev] You are right, as always. I've confirmed that it's included in hive-0.11.0. 
[~ashutoshc] I cannot sure but the optimization seemed not valid. If this will not be fixed
till next release process, we should disabled it by default.

> Multi insert does not work properly with distinct count
> -------------------------------------------------------
>
>                 Key: HIVE-6099
>                 URL: https://issues.apache.org/jira/browse/HIVE-6099
>             Project: Hive
>          Issue Type: Bug
>          Components: Query Processor
>    Affects Versions: 0.9.0, 0.10.0, 0.11.0, 0.12.0
>            Reporter: Pavan Gadam Manohar
>            Assignee: Navis
>              Labels: count, distinct, insert, multi-insert
>         Attachments: explain_hive_0.10.0.txt, with_disabled.txt, with_enabled.txt
>
>
> Need 2 rows to reproduce this Bug. Here are the steps.
> Step 1) Create a table Table_A
> CREATE EXTERNAL TABLE Table_A
> (
> user string
> , type int
> )
> PARTITIONED BY (dt string)
> ROW FORMAT DELIMITED 
> FIELDS TERMINATED BY '|' 
>  STORED AS RCFILE
> LOCATION '/hive/<path>/Table_A';
> Step 2) Scenario: Lets us say consider user tommy belong to both usertypes 111 and 123.
Insert 2 records into the table created above.
> select * from  Table_A;
> hive>  select * from table_a;
> OK
> tommy   123     2013-12-02
> tommy   111     2013-12-02
> Step 3) Create 2 destination tables to simulate multi-insert.
> CREATE EXTERNAL TABLE dest_Table_A
> (
> p_date string
> , Distinct_Users int
> , Type111Users int
> , Type123Users int
> )
> PARTITIONED BY (dt string)
> ROW FORMAT DELIMITED 
> FIELDS TERMINATED BY '|' 
>  STORED AS RCFILE
> LOCATION '/hive/<path>/dest_Table_A';
>  
> CREATE EXTERNAL TABLE dest_Table_B
> (
> p_date string
> , Distinct_Users int
> , Type111Users int
> , Type123Users int
> )
> PARTITIONED BY (dt string)
> ROW FORMAT DELIMITED 
> FIELDS TERMINATED BY '|' 
>  STORED AS RCFILE
> LOCATION '/hive/<path>/dest_Table_B';
> Step 4) Multi insert statement
> from Table_A a
> INSERT OVERWRITE TABLE dest_Table_A PARTITION(dt='2013-12-02')
> select a.dt
> ,count(distinct a.user) as AllDist
> ,count(distinct case when a.type = 111 then a.user else null end) as Type111User
> ,count(distinct case when a.type != 111 then a.user else null end) as Type123User
> group by a.dt
>  
> INSERT OVERWRITE TABLE dest_Table_B PARTITION(dt='2013-12-02')
> select a.dt
> ,count(distinct a.user) as AllDist
> ,count(distinct case when a.type = 111 then a.user else null end) as Type111User
> ,count(distinct case when a.type != 111 then a.user else null end) as Type123User
> group by a.dt
> ;
>  
> Step 5) Verify results.
> hive>  select * from dest_table_a;
> OK
> 2013-12-02      2       1       1       2013-12-02
> Time taken: 0.116 seconds
> hive>  select * from dest_table_b;
> OK
> 2013-12-02      2       1       1       2013-12-02
> Time taken: 0.13 seconds
> Conclusion: Hive gives a count of 2 for distinct users although there is 
> only one distinct user. After trying many datasets observed that Hive is doing Type111Users
+ Typoe123Users = DistinctUsers which is wrong.
> hive> select count(distinct a.user) from table_a a;
> Gives:
> Total MapReduce CPU Time Spent: 4 seconds 350 msec
> OK
> 1



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