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https://issues.apache.org/jira/browse/DRILL-1847?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Hsuan-Yi Chu resolved DRILL-1847.
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Resolution: Fixed
Resolved in commit #: 0368adf0c
> Union All does not match corresponding columns by index to union columns
> ------------------------------------------------------------------------
>
> Key: DRILL-1847
> URL: https://issues.apache.org/jira/browse/DRILL-1847
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Relational Operators
> Reporter: Jason Altekruse
> Assignee: Sean Hsuan-Yi Chu
> Priority: Critical
> Fix For: 0.9.0
>
>
> Union all currently relies on columns to be named the same to merge them,
> this does not follow the behavior of traditional databases. This is a bit
> complicated with Drill, as we do not always know type information up front,
> so validating these queries will have to be less strict. We need to either
> fix this at planning to insert renaming based on the column orderings in the
> query or by changing the behavior of the operator to use the column orders
> that come in. This does not seem to be the best behavior as the engine
> canonicalizes the column order in some cases, so the order is not always
> preserved in the middle of processing, it is reordered at the end to provide
> the correct order to users.
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