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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5298) AvroSerde performance problem caused by HIVE-3833
Date Thu, 26 Sep 2013 17:13:04 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13778980#comment-13778980
] 

Ashutosh Chauhan commented on HIVE-5298:
----------------------------------------

Can you provide more detail? I think pathToPartInfo will really be returning partition directory
(I think variable oneFile is misnamed there). If so, it seems like for loop will have same
# of iterations before and after patch. I don't get from where the perf advantage is coming
from.
                
> 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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