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Bejoy KS commented on HIVE-2540: -------------------------------- The exception is happening when I'm trying to use explode map as well DDL CREATE EXTERNAL TABLE ver_data ( key STRING, id STRING, date_time STRING, model STRING, version STRING, sid STRING, message STRING, tags MAP<STRING,STRING> ); HQL Query SELECT ver_data.*,t1.* FROM ver_data LATERAL VIEW explode(tags) t1 AS param_name,param_value; This Query throws a concurrent modification exception on a LinkedHashMap while doing the join. If I modify the query and avoids the map column('tags') in the retrieval/join,then the query executes successfully. The below modified query executes successfully SELECT ver_data.key, ver_data.id, ver_data.date_time, ver_data.model, ver_data.version, ver_data.sid, ver_data.message, t1.* FROM ver_data LATERAL VIEW explode(tags) t1 AS param_name,param_value; Stack Trace When using Joins on maps with Lateral View 2011-11-07 07:18:22,679 FATAL ExecMapper: org.apache.hadoop.hive.ql.metadata.HiveException: Hive Runtime Error while processing row {"key":"0000","id":"10001",...} at org.apache.hadoop.hive.ql.exec.MapOperator.process(MapOperator.java:546) at org.apache.hadoop.hive.ql.exec.ExecMapper.map(ExecMapper.java:143) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:50) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:391) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:325) at org.apache.hadoop.mapred.Child$4.run(Child.java:270) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:396) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1127) at org.apache.hadoop.mapred.Child.main(Child.java:264) Caused by: java.util.ConcurrentModificationException at java.util.LinkedHashMap$LinkedHashIterator.nextEntry(LinkedHashMap.java:373) at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:392) at java.util.LinkedHashMap$EntryIterator.next(LinkedHashMap.java:391) > LATERAL VIEW with EXPLODE produces ConcurrentModificationException > ------------------------------------------------------------------ > > Key: HIVE-2540 > URL: https://issues.apache.org/jira/browse/HIVE-2540 > Project: Hive > Issue Type: Bug > Components: Query Processor > Affects Versions: 0.7.1 > Reporter: David Phillips > > The following produces {{ConcurrentModificationException}} on the {{for}} > loop inside EXPLODE: > {code} > create table foo as select array(1, 2) a from src limit 1; > select a, x.b from foo lateral view explode(a) x as b; > {code} -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira