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Posted to issues@drill.apache.org by "Sean Hsuan-Yi Chu (JIRA)" <ji...@apache.org> on 2016/03/05 01:13:40 UTC
[jira] [Created] (DRILL-4477) Wrong Plan (potentially wrong result)
if wrapping a query with SELECT * FROM
Sean Hsuan-Yi Chu created DRILL-4477:
----------------------------------------
Summary: 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
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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