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} -- This message was sent by Atlassian JIRA (v6.3.4#6332)