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Date: Thu, 8 Dec 2016 15:46:58 +0000 (UTC)
From: "Abhishek Somani (JIRA)" <jira@apache.org>
To: issues@hive.apache.org
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Subject: [jira] [Comment Edited] (HIVE-15390) Orc reader unnecessarily
 reading stripe footers with hive.optimize.index.filter set to true
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archived-at: Thu, 08 Dec 2016 15:47:00 -0000


    [ https://issues.apache.org/jira/browse/HIVE-15390?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15732553#comment-15732553 ] 

Abhishek Somani edited comment on HIVE-15390 at 12/8/16 3:46 PM:
-----------------------------------------------------------------

Attaching a patch removing the resetting of the maxOffset to Long.MAX_VALUE


was (Author: asomani):
Attaching a patch removing the resetting of the split's maxOffset to Long.MAX_VALUE

> Orc reader unnecessarily reading stripe footers with hive.optimize.index.filter set to true
> -------------------------------------------------------------------------------------------
>
>                 Key: HIVE-15390
>                 URL: https://issues.apache.org/jira/browse/HIVE-15390
>             Project: Hive
>          Issue Type: Bug
>          Components: ORC
>    Affects Versions: 1.2.1
>            Reporter: Abhishek Somani
>            Assignee: Abhishek Somani
>         Attachments: HIVE-15390.patch
>
>
> In a split given to a task, the task's orc reader is unnecessarily reading stripe footers for stripes that are not its responsibility to read. This is happening with hive.optimize.index.filter set to true.
> Assuming one split per task(no tez grouping considered), a task should not need to read beyond the split's end offset. Even in some split computation strategies where a split's end offset can be in the middle of a stripe, it should not need to read more than one stripe beyond the split's end offset(to fully read a stripe that started in it). However I see that some tasks make unnecessary filesystem calls to read all the stripe footers in a file from the split start offset till the end of the file.


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