[
https://issues.apache.org/jira/browse/HIVE-14949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15843743#comment-15843743
]
Alan Gates commented on HIVE-14949:
-----------------------------------
A couple of comments:
UpdateDeleteSemanticAnalyzer.java line 705 (in your patch), how do you know
that the cardinality violation clause will be last in the tree? (We really
need PRs here, so I can comment directly on them)
This looks like it will be quite expensive, since it runs a separate group by
query on the source table. Shouldn't it be off by default rather than on by
default?
> 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
> Attachments: HIVE-14949.01.patch, HIVE-14949.02.patch,
> HIVE-14949.03.patch, HIVE-14949.03.patch, HIVE-14949.04.patch,
> HIVE-14949.05.patch
>
>
> 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
> ISO/IEC 9075-2:2011(E)
> Section 14.2 under "General Rules" Item 6/Subitem a/Subitem 2/Subitem B
> 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
