[jira] [Commented] (HIVE-14949) Enforce that target:source is not 1:N

["Eugene Koifman (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-14949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15660054#comment-15660054 ] 

Eugene Koifman commented on HIVE-14949:
---------------------------------------

Another thought:
generate another leg of the multi-insert stmt like this
Insert into tmp_table select count(*) where <on clause expr> group by target.ROW__ID having count(*) > 1

Then in some final task or post hook, check if the tmp_table is not empty.  


> Enforce that target:source is not 1:N
> -------------------------------------
>
>                 Key: HIVE-14949
>                 URL: https://issues.apache.org/jira/browse/HIVE-14949
>             Project: Hive
>          Issue Type: Sub-task
>          Components: Transactions
>            Reporter: Eugene Koifman
>            Assignee: Eugene Koifman
>
> If > 1 row on source side matches the same row on target side that means that  we are forced update (or delete) the same row in target more than once as part of the same SQL statement.  This should raise an error per SQL Spec
> There is no sure way to do this via static analysis of the query.
> Can we add something to ROJ operator to pay attention to ROW__ID of target side row and compare it with ROW__ID of target side of previous row output?  If they are the same, that means > 1 source row matched.
> Or perhaps just mark each row in the hash table that it matched.  And if it matches again, throw an error.



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