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https://issues.apache.org/jira/browse/HUDI-2923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17453303#comment-17453303
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Danny Chen commented on HUDI-2923:
----------------------------------
Fixed via master branch: 1d4fb827e73b2ae510f0e2c6510a448c0b5bd5b3
> Unable to read from metadata table when a compaction is in progress or has
> failed
> ---------------------------------------------------------------------------------
>
> Key: HUDI-2923
> URL: https://issues.apache.org/jira/browse/HUDI-2923
> Project: Apache Hudi
> Issue Type: Bug
> Reporter: Prashant Wason
> Assignee: Prashant Wason
> Priority: Blocker
> Labels: pull-request-available
> Fix For: 0.10.0
>
>
> When reading from metadata table, the [readers are opened with the latest
> file
> slices|[https://github.com/apache/hudi/blob/master/hudi-common/src/main/java/org/apache/hudi/metadata/HoodieBackedTableMetadata.java#L248].]
>
> When a compaction is in progress, the latest file slice does not have any
> base-file or log file (yet). Hence we are unable to read data from the
> metadata table.
>
> There are two cases here:
> # Compaction eventually completes: We will be able to read data from the
> metadata table.
> # Compaction fails: We will not be able to read data unless the next time
> compaction runs. This can be a fatal issue if the next writer tries to
> perform an update which requires listing partition from the metadata table.
>
> Relevant logs from a unit test:
>
> 13084 [main] INFO
> org.apache.hudi.common.table.view.AbstractTableFileSystemView - *Pending
> Compaction instant for* (FileSlice
> \{fileGroupId=HoodieFileGroupId{partitionPath='files',
> fileId='2733a6ef-4bfd-444d-91bd-b42c3b66a84e-0'}, baseCommitTime=002001,
> baseFile='null', logFiles='[]'}) is
> :Option\{val=(002001,CompactionOperation{baseInstantTime='001',
> dataFileCommitTime=Option{val=001},
> deltaFileNames=[.2733a6ef-4bfd-444d-91bd-b42c3b66a84e-0_001.log.1_0-34-36],
> dataFileName=Option\{val=2733a6ef-4bfd-444d-91bd-b42c3b66a84e-0_0-16-20_001.hfile},
> id='HoodieFileGroupId\{partitionPath='files',
> fileId='2733a6ef-4bfd-444d-91bd-b42c3b66a84e-0'}', metrics={},
> bootstrapFilePath=Optional.empty})}
> 13084 [main] INFO
> org.apache.hudi.common.table.view.AbstractTableFileSystemView - File Slice
> (FileSlice \{fileGroupId=HoodieFileGroupId{partitionPath='files',
> fileId='2733a6ef-4bfd-444d-91bd-b42c3b66a84e-0'}, *baseCommitTime=002001,
> baseFile='null', logFiles='[]'}) is in pending compaction*
>
> 13089 [main] INFO
> org.apache.hudi.common.table.log.HoodieMergedLogRecordScanner - *Number of
> log files scanned => 0*
> 13089 [main] INFO
> org.apache.hudi.common.table.log.HoodieMergedLogRecordScanner -
> MaxMemoryInBytes allowed for compaction => 0
> 13089 [main] INFO
> org.apache.hudi.common.table.log.HoodieMergedLogRecordScanner - Number of
> entries in MemoryBasedMap in ExternalSpillableMap => 0
> 13089 [main] INFO
> org.apache.hudi.common.table.log.HoodieMergedLogRecordScanner - Total size
> in bytes of MemoryBasedMap in ExternalSpillableMap => 0
> 13089 [main] INFO
> org.apache.hudi.common.table.log.HoodieMergedLogRecordScanner - Number of
> entries in DiskBasedMap in ExternalSpillableMap => 0
> 13089 [main] INFO
> org.apache.hudi.common.table.log.HoodieMergedLogRecordScanner - Size of file
> spilled to disk => 0
> 13089 [main] INFO org.apache.hudi.metadata.HoodieBackedTableMetadata -
> *Opened metadata log files from []* at instant (dataset instant=002, metadata
> instant=002) in 2 ms
> 13089 [main] INFO org.apache.hudi.metadata.HoodieBackedTableMetadata -
> Metadata read for key __all_partitions__ took [baseFileRead, logMerge] [0, 0]
> ms
> 13090 [main] INFO org.apache.hudi.metadata.BaseTableMetadata - *Listed
> partitions from metadata: #partitions=0*
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