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https://issues.apache.org/jira/browse/HIVE-8610?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Rui Li updated HIVE-8610:
-------------------------
Attachment: HIVE-8610.3.patch
Update patch according to RB comments.
> Compile time skew join optimization doesn't work with auto map join
> -------------------------------------------------------------------
>
> Key: HIVE-8610
> URL: https://issues.apache.org/jira/browse/HIVE-8610
> Project: Hive
> Issue Type: Bug
> Reporter: Rui Li
> Assignee: Rui Li
> Attachments: HIVE-8610.1.patch, HIVE-8610.2.patch, HIVE-8610.3.patch
>
>
> NPE is thrown if both {{hive.optimize.skewjoin.compiletime}} and
> {{hive.auto.convert.join}} are enabled:
> {code}
> java.lang.NullPointerException
> at
> org.apache.hadoop.hive.ql.optimizer.MapJoinProcessor.convertMapJoin(MapJoinProcessor.java:329)
> at
> org.apache.hadoop.hive.ql.optimizer.MapJoinProcessor.genMapJoinOpAndLocalWork(MapJoinProcessor.java:236)
> at
> org.apache.hadoop.hive.ql.optimizer.physical.CommonJoinTaskDispatcher.convertTaskToMapJoinTask(CommonJoinTaskDispatcher.java:181)
> at
> org.apache.hadoop.hive.ql.optimizer.physical.CommonJoinTaskDispatcher.processCurrentTask(CommonJoinTaskDispatcher.java:463)
> at
> org.apache.hadoop.hive.ql.optimizer.physical.AbstractJoinTaskDispatcher.dispatch(AbstractJoinTaskDispatcher.java:182)
> 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:79)
> at
> org.apache.hadoop.hive.ql.optimizer.physical.PhysicalOptimizer.optimize(PhysicalOptimizer.java:107)
> at
> org.apache.hadoop.hive.ql.parse.MapReduceCompiler.optimizeTaskPlan(MapReduceCompiler.java:275)
> at
> org.apache.hadoop.hive.ql.parse.TaskCompiler.compile(TaskCompiler.java:223)
> at
> org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:10028)
> at
> org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:221)
> at
> org.apache.hadoop.hive.ql.parse.ExplainSemanticAnalyzer.analyzeInternal(ExplainSemanticAnalyzer.java:74)
> at
> org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:221)
> at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:415)
> at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:303)
> at org.apache.hadoop.hive.ql.Driver.compileInternal(Driver.java:1068)
> at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1130)
> at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1005)
> at org.apache.hadoop.hive.ql.Driver.run(Driver.java:995)
> at
> org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:246)
> at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:198)
> at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:408)
> at
> org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:781)
> at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:675)
> 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:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at org.apache.hadoop.util.RunJar.main(RunJar.java:212)
> {code}
> A simple way to reproduce this issue is to add {{set
> hive.auto.convert.join=true}} to one of the skew join qfile, e.g.
> {{skewjoinopt2.q}}.
> While reduce side join can produce correct results, we kind of lost the point
> of skew join optimization - join skewed data via a map join to avoid one
> reducer getting too much records.
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