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Posted to issues@hive.apache.org by "Abhishek Somani (JIRA)" <ji...@apache.org> on 2016/12/08 15:43:59 UTC
[jira] [Updated] (HIVE-15390) Orc reader unnecessarily reading
stripe footers with hive.optimize.index.filter set to true
[ https://issues.apache.org/jira/browse/HIVE-15390?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Abhishek Somani updated HIVE-15390:
-----------------------------------
Attachment: HIVE-15390.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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