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https://issues.apache.org/jira/browse/IMPALA-10785?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17384821#comment-17384821
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Quanlong Huang commented on IMPALA-10785:
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Padding tuples of HdfsScanNode and UnionNode reverts the optimization of
IMPALA-7367. Not sure if we finally gain any improvement. Looking forward to
your test results.
> when union kudu table and hdfs table, union passthrough does not take effect
> ----------------------------------------------------------------------------
>
> Key: IMPALA-10785
> URL: https://issues.apache.org/jira/browse/IMPALA-10785
> Project: IMPALA
> Issue Type: Improvement
> Reporter: pengdou1990
> Priority: Major
>
> IMPALA-3586 already supports union passthrough, and brings great performance
> improvements in union， but there is still some problems when union between
> hdfs table and kudu table ，several points cause the problem:
> # in kudu scanner node output TupleDescriptor, string slot is 16B,while in
> hdfs scanner node output TupleDescriptor, string slot is 12B,cause tuple
> memory layout mismatch
> # in kudu scanner node output TupleDescriptor, string slot is 16B, while in
> Union output TupleDescriptor, string slot is 12B,cause tuple memory layout
> mismatch
> # in Kudu Scannode, row key slot is not null, while in hdfs node, not null
> slot can't get from the metadata, cause tuple memory layout mismatch
> I hive resolved the 1st and 2nd points, how should I do with the 3rd point?
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