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From "Abhishek Somani (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-15390) Orc reader unnecessarily reading stripe footers with hive.optimize.index.filter set to true
Date Fri, 09 Dec 2016 01:59:58 GMT

     [ https://issues.apache.org/jira/browse/HIVE-15390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Abhishek Somani updated HIVE-15390:
-----------------------------------
    Attachment:     (was: HIVE-15390.patch)

> 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
>
> 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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