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https://issues.apache.org/jira/browse/HIVE-5817?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13831960#comment-13831960
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Prasanth J commented on HIVE-5817:
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I came across this exact same issue (column name collision) when I worked on
HIVE-5369. As Ashutosh pointed out tabAlias.colName will work. This is what I
am using for resolving column names from different parent operators. Reference
code can be found in JoinStatsRule under StatsRulesProcFactory.java.
Another option is every operator will have output row schema which has list of
ColumnInfo. ColumnInfo internally contains internal column name and table
alias, when used as a key for hashmap should avoid column name collision. Hope
this helps.
> 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, HIVE-5817.4.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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