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https://issues.apache.org/jira/browse/TAJO-504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13895578#comment-13895578
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Hyunsik Choi commented on TAJO-504:
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The main cause of this issue are two things.
One is there is no output committer. In Tajo, when some task is failed,
QueryMaster retries the task on another node. But, if the task belongs to the
final step that generates output files in HDFS, this error occurs because the
final output file already exists. In order to solve this problem, we have to
implement some kind of output committer which would be similar to that of MR.
The second one is the bug of ColumnPartitionedTableStoreExec. During few weeks,
I have added sort-based column partitioned table executor. which is a default
executor for wring column partiions. It eliminates many problems and it works
well. I think that the second one was resolved.
So, the remain issue is only output committer. I'll create the issue in order
to clearfy what we should do, and I close this issue as not a problem.
Thank you Min for this report!
> when inserting to a column partitioned table, if a queryunit attempt fails,
> an AlreadyExistsStorageException will throw
> -----------------------------------------------------------------------------------------------------------------------
>
> Key: TAJO-504
> URL: https://issues.apache.org/jira/browse/TAJO-504
> Project: Tajo
> Issue Type: Bug
> Components: distributed query plan
> Reporter: Min Zhou
> Fix For: 0.8-incubating
>
>
> I came across such exception these days.
> ColumnPartitionedTableStoreExec creates hdfs directories based on partition
> values. For example is one of the partitions is 'col1=2', a directory named
> 'col1=2' will be created. If query unit attempt fails, that directory still
> exist. After that TajoQueryMaster start another query unit attempt to
> reprocessing the logic in ColumnPartitionedTableStoreExec. This physical
> executor try to create 'col1=2' again, but before creating, it found the
> target directory already exist, it will throw an
> AlreadyExistsStorageException. And eventually, the query fails.
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