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Date: Sat, 19 Nov 2016 00:43:58 +0000 (UTC)
From: "Ashu Pachauri (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
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Subject: [jira] [Updated] (HBASE-17117) Reversed scan returns deleted
 versions and breaks RegionLocator
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archived-at: Sat, 19 Nov 2016 00:44:00 -0000


     [ https://issues.apache.org/jira/browse/HBASE-17117?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ashu Pachauri updated HBASE-17117:
----------------------------------
    Attachment: reverseScanMetaDeleteFamily

reverseScanMetaDeleteFamily : Output of raw, forward and reversed scan on meta during the issue.
I have replaced the start and end keys with dummy values (but in correct order).

We did not back up the store files for meta, and I am unable to reproduce the issue just by creating a delete family marker in meta and doing a reverse scan. This is not happening consistently during splits either.  So, I am dropping the priority down to major from blocker. I'll try to research edge cases in the scanner code and come up with a unit test for reproducing this. Any ideas are welcome.

> Reversed scan returns deleted versions and breaks RegionLocator
> ---------------------------------------------------------------
>
>                 Key: HBASE-17117
>                 URL: https://issues.apache.org/jira/browse/HBASE-17117
>             Project: HBase
>          Issue Type: Bug
>          Components: Scanners
>    Affects Versions: 1.3.0
>            Reporter: Ashu Pachauri
>            Priority: Blocker
>             Fix For: 1.3.0
>
>         Attachments: reverseScanMetaDeleteFamily
>
>
> We started seeing clients persistently throwing errors as they were trying to talk to a region that was non existent (split a few days ago). We verified that the region was deleted from meta when the split happened.
> On performing a raw scan on meta, the deleted version for the split region appears, which also does on performing a normal reversed scan. Since MetaScanner uses a reversed scan, this explains why clients see non existent regions.
> We also verified that there was no in-memory corrupt state by failing over the master. When we trigger major compaction on meta, the problem goes away further confirming the fact that we were seeing deleted versions.


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