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https://issues.apache.org/jira/browse/HIVE-18429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16323020#comment-16323020
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Prasanth Jayachandran commented on HIVE-18429:
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I don't the understand the part where we create .empty file? what is the
purpose of it? Why no create directory for TMP_LOCATION using direct FS api
when it does not exist?
> Compaction should handle a case when it produces no output
> ----------------------------------------------------------
>
> Key: HIVE-18429
> URL: https://issues.apache.org/jira/browse/HIVE-18429
> Project: Hive
> Issue Type: Bug
> Components: Transactions
> Affects Versions: 1.0.0
> Reporter: Eugene Koifman
> Assignee: Eugene Koifman
> Attachments: HIVE-18429.01.patch, HIVE-18429.02.patch
>
>
> Suppose we start with empty delta_8_8 and delta_9_9 and compaction runs.
> It will currently produce an MR job with 0 splits and so
> {{CompactorMR.TMP_LOCATION}} never gets created. This causes
> {{CompactorOutputCommitted.commitJob()}} to fail when it tries to do
> {{FileStatus[] contents = fs.listStatus(tmpLocation);}} since tmpLocation
> doesn't exist.
> If compactor fails to produce delta_8_9 here it will fail to do further
> compaction unless new delta with data is created.
> If the number of empty deltas is > than
> HiveConf.ConfVars.COMPACTOR_MAX_NUM_DELTA, compaction will not be able to
> proceed at all.
> It should produce a delta_8_9 in this case even if it's empty.
> The error (in the log of standalone metastore process) would look like this
> {noformat}
> 2017-12-27 17:19:28,850 ERROR CommitterEvent Processor #1
> org.apache.hadoop.mapreduce.v2.app.commit.CommitterEventHandler: Could not
> commit job
> java.io.FileNotFoundException: File
> hdfs://OTCHaaS/apps/hive/warehouse/momi.db/sensor_data/babyid=5911806ebf69640100004257/_tmp_b4c5a3f3-44e5-4d45-86af-5b773bf0fc96
> does not exist.
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.listStatusInternal(DistributedFileSystem.java:923)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.access$600(DistributedFileSystem.java:114)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem$22.doCall(DistributedFileSystem.java:985)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem$22.doCall(DistributedFileSystem.java:981)
> at
> org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.listStatus(DistributedFileSystem.java:992)
> at
> rg.apache.hadoop.hive.ql.txn.compactor.CompactorMR$CompactorOutputCommitter.commitJob(CompactorMR.java:785)
> at
> org.apache.hadoop.mapred.OutputCommitter.commitJob(OutputCommitter.java:291)
> at
> org.apache.hadoop.mapreduce.v2.app.commit.CommitterEventHandler$EventProcessor.handleJobCommit(CommitterEventHandler.java:285)
> at
> org.apache.hadoop.mapreduce.v2.app.commit.CommitterEventHandler$EventProcessor.run(CommitterEventHandler.java:237)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
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