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From "Remus Rusanu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5817) column name to index mapping in VectorizationContext is broken
Date Fri, 22 Nov 2013 19:22:35 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13830247#comment-13830247
] 

Remus Rusanu commented on HIVE-5817:
------------------------------------

I think the only real problem operator is JOIN. Is not necessarily ‘one VC per operator’
but more like ‘one VC per query region’ where query region is defined by boundaries between
different VS requirements (basically different result shapes). An operator like JOIN is one
that clearly introduces a boundary, and the interesting part is that it needs two vectorization
contexts: one for it’s input(s) and one for it’s output. So it would be more along the
line that during vectorization each operator takes an VC (for its input, provided by its parent
operator) and gives out a VC for its output, for its child operators to consume. Most operators
would give out the same VC they get as input (ie. they do not change shape). And there is
serialization too, which is handled separately (as properties added to the Map).

I'll try to come up with actual code over this week end.

> 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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