Hive insert query with dynamic partitioning - hadoop

Question

I have an orc formatted partitioned and clustered hive table to which I have to insert data from a temp table.
Create table statements:
orc table:
CREATE EXTERNAL TABLE DYN_TGT_TABLE(ID INT,USRNAME VARCHAR(20), LD TIMESTAMP) PARTITIONED BY (PART VARCHAR(20)) CLUSTERED BY (id) INTO 1024 BUCKETS ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.orc.OrcSerde' STORED AS INPUTFORMAT 'org.apache.hadoop.hive.ql.io.orc.OrcInputFormat' OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat' LOCATION '/tmp/dyn_tgt_table' TBLPROPERTIES ('transactional'='true','transient_lastDdlTime'='1461157247');
temp table:
CREATE EXTERNAL TABLE DYN_TEMP_TABLE(ID INT,USRNAME VARCHAR(20),PART VARCHAR(20), LD TIMESTAMP) ROW FORMAT DELIMITED FIELDS TERMINATED BY '|' STORED AS TEXTFILE LOCATION '/tmp/dyn_temp_table' TBLPROPERTIES ('transactional'='TRUE','transient_lastDdlTime'='1461216088');
Added 5 records to temp table:
hive> select * from DYN_TEMP_TABLE;
OK
1 user1 A 2016-05-06 06:31:48
2 user2 A 2016-05-06 06:31:48
14 user3 B 2016-05-06 06:31:48
15 user4 B 2016-05-06 06:31:48
16 user5 B 2016-05-06 06:31:48
Time taken: 0.166 seconds, Fetched: 5 row(s)
The below dynamic insert query is erroring:
insert into TABLE DYN_TGT_TABLE PARTITION(part) select id,usrname,ld,part from DYN_TEMP_TABLE;
Error message:
Diagnostic Messages for this Task:
Error: java.lang.RuntimeException: org.apache.hadoop.hive.ql.metadata.HiveException: Hive Runtime Error while processing row (tag=0)
{"key":{},"value":{"_col0":15,"_col1":"user4","_col2":"2016-05-06 06:31:48","_col3":"B"}}
at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.reduce(ExecReducer.java:265)
at org.apache.hadoop.mapred.ReduceTask.runOldReducer(ReduceTask.java:444)
at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:392)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: Hive Runtime Error while processing row (tag=0) {"key":{},"value":{"_col0":15,"_col1":"user4","_col2":"2016-05-06 06:31:48","_col3":"B"}}
at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.reduce(ExecReducer.java:253)
... 7 more
Caused by: java.lang.NullPointerException
at org.apache.hadoop.hive.ql.exec.FileSinkOperator.findWriterOffset(FileSinkOperator.java:755)
at org.apache.hadoop.hive.ql.exec.FileSinkOperator.processOp(FileSinkOperator.java:683)
at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:815)
at org.apache.hadoop.hive.ql.exec.ExtractOperator.processOp(ExtractOperator.java:45)
at org.apache.hadoop.hive.ql.exec.mr.ExecReducer.reduce(ExecReducer.java:244)
... 7 more
FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.mr.MapRedTask
Please help me point out the cause for this error.