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https://issues.apache.org/jira/browse/HIVE-5817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13831541#comment-13831541
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Remus Rusanu commented on HIVE-5817:
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I have the implementation of 'vectorization regions" almost done and I know
how to finish it. Will post a patch tomorrow.
Using the qualified column names (alias + column) will work probably, I don't
think a query can have duplicate aliases (not up to par on my ANSI readings one
can tell...). Thing is that will ripple everywhere in the vectorization
context, we'll have to modify all the expression builders to use the
alias.column as a key. If the "region concept" will work, will have a much more
contained impact.
> 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
> Reporter: Sergey Shelukhin
> Assignee: Remus Rusanu
> Priority: Critical
> Attachments: HIVE-5817-uniquecols.broken.patch,
> HIVE-5817.00-broken.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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