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https://issues.apache.org/jira/browse/HIVE-5817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13841981#comment-13841981
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Sergey Shelukhin commented on HIVE-5817:
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It seems like I cannot make a repro for select... even though there are name
collisions, the mappings are correct. Perhaps when someone finds a bug we can
solve it :)
> column name to index mapping in VectorizationContext is broken
> --------------------------------------------------------------
>
> Key: HIVE-5817
> URL: https://issues.apache.org/jira/browse/HIVE-5817
> Project: Hive
> Issue Type: Bug
> Components: Vectorization
> Affects Versions: 0.13.0
> Reporter: Sergey Shelukhin
> Assignee: Remus Rusanu
> Priority: Critical
> Fix For: 0.13.0
>
> Attachments: HIVE-5817-uniquecols.broken.patch,
> HIVE-5817.00-broken.patch, HIVE-5817.4.patch, HIVE-5817.5.patch,
> HIVE-5817.6.patch
>
>
> Columns coming from different operators may have the same internal names
> ("_colNN"). There exists a query in the form {{select b.cb, a.ca from a JOIN
> b ON ... JOIN x ON ...;}} (distilled from a more complex query), which runs
> ok w/o vectorization. With vectorization, it will run ok for most ca, but for
> some ca it will fail (or can probably return incorrect results). That is
> because when building column-to-VRG-index map in VectorizationContext,
> internal column name for ca that the first map join operator adds to the
> mapping may be the same as internal name for cb that the 2nd one tries to
> add. 2nd VMJ doesn't add it (see code in ctor), and when it's time for it to
> output stuff, it retrieves wrong index from the map by name, and then wrong
> vector from VRG.
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