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Posted to dev@hive.apache.org by "Amareshwari Sriramadasu (JIRA)" <ji...@apache.org> on 2013/02/27 12:21:14 UTC
[jira] [Commented] (HIVE-3952) merge map-job followed by map-reduce
job
[ https://issues.apache.org/jira/browse/HIVE-3952?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13588233#comment-13588233 ]
Amareshwari Sriramadasu commented on HIVE-3952:
-----------------------------------------------
Tried out the patch, when we run query like the following :
INSERT OVERWRITE DIRECTORY "/dir"
Select ....
It fails with exception :
{noformat}
java.lang.ClassCastException: org.apache.hadoop.hive.ql.exec.MoveTask cannot be cast to org.apache.hadoop.hive.ql.exec.MapRedTask
at org.apache.hadoop.hive.ql.optimizer.physical.CommonJoinResolver$CommonJoinTaskDispatcher.mayBeMergeMapJoinTaskWithMapReduceTask(CommonJoinResolver.java:291)
at org.apache.hadoop.hive.ql.optimizer.physical.CommonJoinResolver$CommonJoinTaskDispatcher.processCurrentTask(CommonJoinResolver.java:535)
at org.apache.hadoop.hive.ql.optimizer.physical.CommonJoinResolver$CommonJoinTaskDispatcher.dispatch(CommonJoinResolver.java:701)
at org.apache.hadoop.hive.ql.lib.TaskGraphWalker.dispatch(TaskGraphWalker.java:111)
at org.apache.hadoop.hive.ql.lib.TaskGraphWalker.walk(TaskGraphWalker.java:194)
at org.apache.hadoop.hive.ql.lib.TaskGraphWalker.startWalking(TaskGraphWalker.java:139)
at org.apache.hadoop.hive.ql.optimizer.physical.CommonJoinResolver.resolve(CommonJoinResolver.java:113)
at org.apache.hadoop.hive.ql.optimizer.physical.PhysicalOptimizer.optimize(PhysicalOptimizer.java:79)
at org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.genMapRedTasks(SemanticAnalyzer.java:8138)
at org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:8470)
at org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:259)
at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:431)
at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:335)
at org.apache.hadoop.hive.ql.Driver.run(Driver.java:898)
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:413)
at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:756)
at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:614)
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:197)
{noformat}
> merge map-job followed by map-reduce job
> ----------------------------------------
>
> Key: HIVE-3952
> URL: https://issues.apache.org/jira/browse/HIVE-3952
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: Vinod Kumar Vavilapalli
> Attachments: HIVE-3952-20130226.txt
>
>
> Consider the query like:
> select count(*) FROM
> ( select idOne, idTwo, value FROM
> bigTable
> JOIN
> smallTableOne on (bigTable.idOne = smallTableOne.idOne)
> ) firstjoin
> JOIN
> smallTableTwo on (firstjoin.idTwo = smallTableTwo.idTwo);
> where smallTableOne and smallTableTwo are smaller than hive.auto.convert.join.noconditionaltask.size and
> hive.auto.convert.join.noconditionaltask is set to true.
> The joins are collapsed into mapjoins, and it leads to a map-only job
> (for the map-joins) followed by a map-reduce job (for the group by).
> Ideally, the map-only job should be merged with the following map-reduce job.
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