[ https://issues.apache.org/jira/browse/HIVE-3496?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Namit Jain updated HIVE-3496: ----------------------------- Resolution: Fixed Hadoop Flags: Reviewed Status: Resolved (was: Patch Available) Committed. Thanks Kevin > Query plan for multi-join where the third table joined is a subquery > containing a map-only union with hive.auto.convert.join=true is wrong > ------------------------------------------------------------------------------------------------------------------------------------------ > > Key: HIVE-3496 > URL: https://issues.apache.org/jira/browse/HIVE-3496 > Project: Hive > Issue Type: Bug > Components: Query Processor > Affects Versions: 0.10.0 > Reporter: Kevin Wilfong > Assignee: Kevin Wilfong > Fix For: 0.10.0 > > Attachments: HIVE-3496.1.patch.txt > > > Take the following query as an example: > EXPLAIN SELECT * FROM > src11 a JOIN > src12 b ON (a.key = b.key) JOIN > (SELECT * FROM (SELECT * FROM src13 UNION ALL SELECT * FROM src14)a )c ON > c.value = b.value; > When hive.auto.convert.join=true, the two joins are implemented separately as > conditional tasks with two mapjoins and a backup common join. In the second > join, the conditional task will be a backup task, contained in the > ConditionalTask, and a root task. This is clearly wrong, and leads to query > failures. > I've traced this to the joinUnionPlan method of GenMapRedUtils. If the union > operator was performed in its own map reduce task and it could be a root > task, when it is added to the mapper of the existing task which performs the > join in the reducer, this task will get made a root task without first > checking if the existing (non-union) task has any dependencies. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira