I have following query with 2 parquet tables (t_par_string, t_par_datatype). select count(*) from ( select max(source) source, col1, col2, col3 . . . col149,col150 , count(*) from ( select 1 source, col1, col2, col3 . . . col149,col150 from t_par_string union all select 1 source, col1, col2, col3 . . . col149,col150 from t_par_datatype ) merged_data group by col1, col2, col3 . . . col149,col150 having count(*) = 1 ) minus_data where source = 1 It is failed with following error Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: Hive Runtime Error while processing row at org.apache.hadoop.hive.ql.exec.MapOperator.process(MapOperator.java:507) at org.apache.hadoop.hive.ql.exec.mr.ExecMapper.map(ExecMapper.java:170) ... 8 more Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: Unable to execute method public org.apache.hadoop.io.Text org.apache.hadoop.hive.ql.udf.UDFToString.evaluate(org.apache.hadoop.hive.serde2.io.TimestampWritable) on object org.apache.hadoop.hive.ql.udf.UDFToString@134ff8f8 of class org.apache.hadoop.hive.ql.udf.UDFToString with arguments {2015-10-17 00:00:00:org.apache.hadoop.hive.serde2.io.TimestampWritable} of size 1 at org.apache.hadoop.hive.ql.exec.FunctionRegistry.invoke(FunctionRegistry.java:989) at org.apache.hadoop.hive.ql.udf.generic.GenericUDFBridge.evaluate(GenericUDFBridge.java:182) at org.apache.hadoop.hive.ql.exec.ExprNodeGenericFuncEvaluator._evaluate(ExprNodeGenericFuncEvaluator.java:186) at org.apache.hadoop.hive.ql.exec.ExprNodeEvaluator.evaluate(ExprNodeEvaluator.java:77) at org.apache.hadoop.hive.ql.exec.ExprNodeEvaluator.evaluate(ExprNodeEvaluator.java:65) at org.apache.hadoop.hive.ql.exec.SelectOperator.processOp(SelectOperator.java:77) at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:815) at org.apache.hadoop.hive.ql.exec.TableScanOperator.processOp(TableScanOperator.java:97) at org.apache.hadoop.hive.ql.exec.MapOperator$MapOpCtx.forward(MapOperator.java:157) at org.apache.hadoop.hive.ql.exec.MapOperator.process(MapOperator.java:497) ... 9 more Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.hive.ql.exec.FunctionRegistry.invoke(FunctionRegistry.java:965) ... 18 more Caused by: java.lang.OutOfMemoryError: GC overhead limit exceeded at java.util.Arrays.copyOf(Arrays.java:3181) at java.text.DateFormatSymbols.copyMembers(DateFormatSymbols.java:850) at java.text.DateFormatSymbols.initializeData(DateFormatSymbols.java:758) at java.text.DateFormatSymbols.<init>(DateFormatSymbols.java:145) at sun.util.locale.provider.DateFormatSymbolsProviderImpl.getInstance(DateFormatSymbolsProviderImpl.java:85) at java.text.DateFormatSymbols.getProviderInstance(DateFormatSymbols.java:364) at java.text.DateFormatSymbols.getInstance(DateFormatSymbols.java:340) at java.util.Calendar.getDisplayName(Calendar.java:2110) at java.text.SimpleDateFormat.subFormat(SimpleDateFormat.java:1125) at java.text.SimpleDateFormat.format(SimpleDateFormat.java:966) at java.text.SimpleDateFormat.format(SimpleDateFormat.java:936) at java.text.DateFormat.format(DateFormat.java:345) at org.apache.hadoop.hive.serde2.io.TimestampWritable.toString(TimestampWritable.java:383) at org.apache.hadoop.hive.ql.udf.UDFToString.evaluate(UDFToString.java:150) at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.apache.hadoop.hive.ql.exec.FunctionRegistry.invoke(FunctionRegistry.java:965) at org.apache.hadoop.hive.ql.udf.generic.GenericUDFBridge.evaluate(GenericUDFBridge.java:182) at org.apache.hadoop.hive.ql.exec.ExprNodeGenericFuncEvaluator._evaluate(ExprNodeGenericFuncEvaluator.java:186) at org.apache.hadoop.hive.ql.exec.ExprNodeEvaluator.evaluate(ExprNodeEvaluator.java:77) at org.apache.hadoop.hive.ql.exec.ExprNodeEvaluator.evaluate(ExprNodeEvaluator.java:65) at org.apache.hadoop.hive.ql.exec.SelectOperator.processOp(SelectOperator.java:77) at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:815) at org.apache.hadoop.hive.ql.exec.TableScanOperator.processOp(TableScanOperator.java:97) at org.apache.hadoop.hive.ql.exec.MapOperator$MapOpCtx.forward(MapOperator.java:157) at org.apache.hadoop.hive.ql.exec.MapOperator.process(MapOperator.java:497) at org.apache.hadoop.hive.ql.exec.mr.ExecMapper.map(ExecMapper.java:170) at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:54) at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:453) at org.apache.hadoop.mapred.MapTask.run(MapTask.java:343) at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:164) ... View more