[ https://issues.apache.org/jira/browse/HIVE-29166 ]


    Dmitriy Fingerman deleted comment on HIVE-29166:
    ------------------------------------------

was (Author: JIRAUSER295017):
The attached sql script with a repeated MERGE query generates duplicates.

If any of the following 2 changes are done to the script than there are no 
duplicates:
 # hive.auto.convert.join=true –> hive.auto.convert.join=false
 # The order of columns in CLUSTER BY doesn't match the order of columns in 
CREATE TABLE. If the order matches then there are no duplicates.

It was also found that a query like below returns wrong results:
{code:java}
select * from omsexternal_order_mapping_backup 
left outer join omsexternal_order_mapping__2025_08_26_03__transactional on 
...{code}
This is what MERGE query does under the hood.

> Repeated MERGE query generates duplicates
> -----------------------------------------
>
>                 Key: HIVE-29166
>                 URL: https://issues.apache.org/jira/browse/HIVE-29166
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Dmitriy Fingerman
>            Priority: Major
>         Attachments: merge_duplicates.q
>
>
> The attached sql script with a repeated MERGE query generates duplicates.
> If any of the following 2 changes are done to the script than there are no 
> duplicates:
>  # hive.auto.convert.join=true –> hive.auto.convert.join=false
>  # The order of columns in CLUSTER BY doesn't match the order of columns in 
> CREATE TABLE. If the order matches then there are no duplicates.
> It was also found that a query like below returns wrong results:
> {code:java}
> select * from omsexternal_order_mapping_backup 
> left outer join omsexternal_order_mapping__2025_08_26_03__transactional on 
> ...{code}
> This is what MERGE query does under the hood.



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