hive> select product_id, track_time from trackinfo limit 5;                    
Total MapReduce jobs = 1
Launching Job 1 out of 1
Number of reduce tasks is set to 0 since there's no reduce operator
org.apache.hadoop.ipc.RemoteException: java.io.IOException: java.io.IOException: The number of tasks for this job 156028 exceeds the configured limit 5000
        at org.apache.hadoop.mapred.JobTracker.submitJob(JobTracker.java:3943)
        at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:563)
        at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388)
        at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:396)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1093)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1382)
Caused by: java.io.IOException: The number of tasks for this job 156028 exceeds the configured limit 5000
        at org.apache.hadoop.mapred.JobInProgress.checkTaskLimits(JobInProgress.java:509)
        at org.apache.hadoop.mapred.JobInProgress.<init>(JobInProgress.java:485)
        at org.apache.hadoop.mapred.JobTracker.submitJob(JobTracker.java:3941)
        ... 10 more

        at org.apache.hadoop.ipc.Client.call(Client.java:1066)
        at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:225)
        at org.apache.hadoop.mapred.$Proxy11.submitJob(Unknown Source)
        at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:921)
        at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:850)
        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:1093)
        at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:850)
        at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:824)
        at org.apache.hadoop.hive.ql.exec.ExecDriver.execute(ExecDriver.java:447)
        at org.apache.hadoop.hive.ql.exec.MapRedTask.execute(MapRedTask.java:136)
        at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:138)
        at org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:57)
        at org.apache.hadoop.hive.ql.Driver.launchTask(Driver.java:1336)
        at org.apache.hadoop.hive.ql.Driver.execute(Driver.java:1122)
        at org.apache.hadoop.hive.ql.Driver.run(Driver.java:935)
        at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:259)
        at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:216)
        at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:412)
        at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:755)
        at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:613)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
Job Submission failed with exception 'org.apache.hadoop.ipc.RemoteException(java.io.IOException: java.io.IOException: The number of tasks for this job 156028 exceeds the configured limit 5000
        at org.apache.hadoop.mapred.JobTracker.submitJob(JobTracker.java:3943)
        at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:563)
        at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388)
        at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384)
        at java.security.AccessController.doPrivileged(Native Method)
        at javax.security.auth.Subject.doAs(Subject.java:396)
        at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1093)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1382)
Caused by: java.io.IOException: The number of tasks for this job 156028 exceeds the configured limit 5000
        at org.apache.hadoop.mapred.JobInProgress.checkTaskLimits(JobInProgress.java:509)
        at org.apache.hadoop.mapred.JobInProgress.<init>(JobInProgress.java:485)
        at org.apache.hadoop.mapred.JobTracker.submitJob(JobTracker.java:3941)
        ... 10 more
)'
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.MapRedTask



错误原因：
因为trackinfo表的数据太庞大，并且写的sql语句
select product_id, track_time from trackinfo limit 5
性能耗损太大了，将会导致调度的Map数太多，超出了job的限制。

来看看hive中trackinfo表的数据量有多大：
-bash-3.2$ hadoop fs -dus /data/share/trackinfo
Warning: $HADOOP_HOME is deprecated.

hdfs://yhd-hadoop06.int.yihaodian.com:9000/data/share/trackinfo 19387740988708
能够看到，trackinfo的数据量大概有19TB这么大

改写sql语句，指定where条件，性能得到了提升
select product_id, track_time from trackinfo where ds='2014-5-13' limit 5
问题同一时候也被攻克了