cloudera中hive查询的问题

Question

我可以在 hive 中执行所有其他查询，但是当我执行 join 时，它就会卡住。

hive> select count (*) from tab10 join tab1;
Warning: Map Join MAPJOIN[13][bigTable=tab10] in task 'Stage-2:MAPRED' is a cross product
Query ID = root_20160406145959_b57642e0-7499-41a0-914c-0004774fe4ac
Total jobs = 1
Execution log at: /tmp/root/root_20160406145959_b57642e0-7499-41a0-914c-0004774fe4ac.log
2016-04-06 03:00:03 Starting to launch local task to process map join;  maximum memory = 2058354688

2016-04-06 03:00:03 Dump the side-table for tag: 1 with group count: 1 into file: file:/tmp/root/b71aa45b-f356-4a54-a880-77e57cd53ed3/hive_2016-04-06_14-59-59_858_3722397802100174236-1/-local-10004/HashTable-Stage-2/MapJoin-mapfile01--.hashtable
2016-04-06 03:00:03 Uploaded 1 File to: file:/tmp/root/b71aa45b-f356-4a54-a880-77e57cd53ed3/hive_2016-04-06_14-59-59_858_3722397802100174236-1/-local-10004/HashTable-Stage-2/MapJoin-mapfile01--.hashtable (280 bytes)
2016-04-06 03:00:03 End of local task; Time Taken: 0.562 sec.

此时它已挂起，并且根本不会产生任何 map reduce 任务。有什么问题？

我确实在 hive.log 中看到了这一点。

2016-04-06 15:00:00,124 INFO  [main]: ql.Driver (Driver.java:launchTask(1643)) - Starting task [Stage-5:MAPREDLOCAL] in serial mode
2016-04-06 15:00:00,125 INFO  [main]: mr.MapredLocalTask (MapredLocalTask.java:executeInChildVM(159)) - Generating plan file file:/tmp/root/b71aa45b-f356-4a54-a880-77e57cd53ed3/hive_2016-04-06_14-59-59_858_3722397802100174236-1/-local-10006/plan.xml
2016-04-06 15:00:00,233 INFO  [main]: mr.MapredLocalTask (MapredLocalTask.java:executeInChildVM(288)) - Executing: /opt/cloudera/parcels/CDH-5.5.2-1.cdh5.5.2.p0.4/lib/hadoop/bin/hadoop jar /opt/cloudera/parcels/CDH-5.5.2-1.cdh5.5.2.p0.4/jars/hive-exec-1.1.0-cdh5.5.2.jar org.apache.hadoop.hive.ql.exec.mr.ExecDriver -localtask -plan file:/tmp/root/b71aa45b-f356-4a54-a880-77e57cd53ed3/hive_2016-04-06_14-59-59_858_3722397802100174236-1/-local-10006/plan.xml   -jobconffile file:/tmp/root/b71aa45b-f356-4a54-a880-77e57cd53ed3/hive_2016-04-06_14-59-59_858_3722397802100174236-1/-local-10007/jobconf.xml

除此之外没有什么。有谁知道如何解决这个问题？

Answer 1

打开mapred-site.xml文件并添加属性：

<property>
<name>mapred.child.java.opts</name>
<value>-Xmx1024m</value>

您需要增加 hadoop JVM 使用的堆内存