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https://issues.apache.org/jira/browse/HIVE-5298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13782176#comment-13782176
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Xuefu Zhang commented on HIVE-5298:
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[~hsubramaniyan] Thanks for your comments. I think what Ashutosh meant above
was that the path in conf.getPathToAliases() is the partition directory, not
individual file for the partition. Thus, the number of entries from calling
conf.getPathToAliases() is the same as what my modified code change will get. I
verified that Ashutosh's point is correct. Did you see any evidence of
conf.getPathToAliases() returning each data file as entries?
> AvroSerde performance problem caused by HIVE-3833
> -------------------------------------------------
>
> Key: HIVE-5298
> URL: https://issues.apache.org/jira/browse/HIVE-5298
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Affects Versions: 0.11.0
> Reporter: Xuefu Zhang
> Assignee: Xuefu Zhang
> Fix For: 0.13.0
>
> Attachments: HIVE-5298.1.patch, HIVE-5298.patch
>
>
> HIVE-3833 fixed the targeted problem and made Hive to use partition-level
> metadata to initialize object inspector. In doing that, however, it goes thru
> every file under the table to access the partition metadata, which is very
> inefficient, especially in case of multiple files per partition. This causes
> more problem for AvroSerde because AvroSerde initialization accesses schema,
> which is located on file system. As a result, before hive can process any
> data, it needs to access every file for a table, which can take long enough
> to cause job failure because of lack of job progress.
> The improvement can be made so that partition metadata is only access once
> per partition.
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