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https://issues.apache.org/jira/browse/DRILL-4477?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zelaine Fong updated DRILL-4477:
--------------------------------
Priority: Major (was: Blocker)
> Wrong Plan (potentially wrong result) if wrapping a query with SELECT * FROM
> ----------------------------------------------------------------------------
>
> Key: DRILL-4477
> URL: https://issues.apache.org/jira/browse/DRILL-4477
> Project: Apache Drill
> Issue Type: Bug
> Components: Query Planning & Optimization
> Reporter: Sean Hsuan-Yi Chu
> Assignee: Sean Hsuan-Yi Chu
> Fix For: Future
>
> Attachments: t1.json, t2.json
>
>
> For example, a query
> {code}
> select * from (select s.name, v.name, v.registration from
> cp.`tpch/region.parquet` s left outer join cp.`tpch/nation.parquet` v
> on (s.name = v.name)
> where s.age < 30) t
> {code}
> gives a plan as below:
> {code}
> +------+------+
> | text | json |
> +------+------+
> | 00-00 Screen
> 00-01 Project(name=[$0], name0=[$1], registration=[$2])
> 00-02 Project(name=[$0], name0=[$0], registration=[$3])
> 00-03 Project(name=[$2], age=[$3], name0=[$0], registration=[$1])
> 00-04 HashJoin(condition=[=($2, $0)], joinType=[right])
> 00-06 Scan(groupscan=[ParquetGroupScan
> [entries=[ReadEntryWithPath [path=classpath:/tpch/nation.parquet]],
> selectionRoot=classpath:/tpch/nation.parquet, numFiles=1,
> usedMetadataFile=false, columns=[`name`, `registration`]]])
> 00-05 Project(name0=[$0], age=[$1])
> 00-07 SelectionVectorRemover
> 00-08 Filter(condition=[<($1, 30)])
> 00-09 Scan(groupscan=[ParquetGroupScan
> [entries=[ReadEntryWithPath [path=classpath:/tpch/region.parquet]],
> selectionRoot=classpath:/tpch/region.parquet, numFiles=1,
> usedMetadataFile=false, columns=[`name`, `age`]]])
> {code}
> In the line 00-02, both name and name0 point at the same incoming column
> (probably due to the JOIN CONDITION).
> However. the fact that these two are the JOIN condition does not make a case
> that they must be equal since implicit casting might be invoked to perform
> the JOIN condition.
> Interestingly, if the SELECT * FROM wrapper is removed, this bug won't be
> exposed:
> {code}
> select s.name, v.name, v.registration from cp.`tpch/region.parquet` s left
> outer join cp.`tpch/nation.parquet` v on (s.name = v.name)
> where s.age < 30
> {code}
> gives
> {code}
> 00-00 Screen
> 00-01 Project(name=[$0], name0=[$1], registration=[$2])
> 00-02 Project(name=[$2], name0=[$0], registration=[$1])
> 00-03 HashJoin(condition=[=($2, $0)], joinType=[right])
> 00-05 Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath
> [path=classpath:/tpch/nation.parquet]],
> selectionRoot=classpath:/tpch/nation.parquet, numFiles=1,
> usedMetadataFile=false, columns=[`name`, `registration`]]])
> 00-04 Project(name0=[$0])
> 00-06 Project(name=[$0])
> 00-07 SelectionVectorRemover
> 00-08 Filter(condition=[<($1, 30)])
> 00-09 Scan(groupscan=[ParquetGroupScan
> [entries=[ReadEntryWithPath [path=classpath:/tpch/region.parquet]],
> selectionRoot=classpath:/tpch/region.parquet, numFiles=1,
> usedMetadataFile=false, columns=[`name`, `age`]]])
> {code}
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