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https://issues.apache.org/jira/browse/PHOENIX-3326?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Samarth Jain updated PHOENIX-3326:
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    Attachment: PHOENIX-3326_4.8-HBase-0.98.patch

Patch for the 4.8 branch.

> Restoring SYSTEM.CATALOG from snapshot causes clients to run into 
> UpgradeInProgressException
> --------------------------------------------------------------------------------------------
>
>                 Key: PHOENIX-3326
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-3326
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Samarth Jain
>            Assignee: Samarth Jain
>         Attachments: PHOENIX-3326_4.8-HBase-0.98.patch, PHOENIX-3326_wip.patch
>
>
> We create a snapshot of the SYSTEM.CATALOG table only after the client is 
> able to successfully acquire a distributed mutex of sorts. This means the 
> snapshot also ends up containing the row that serves as the mutex. Now when 
> restoring the table from snapshot, this rows is still present which causes 
> clients to throw UpgradeInProgress exception. 
> I can think of a couple of ways to fix this:
> 1) Do the checkAndPut for the UPGRADE_MUTEX after creating the snapshot. I am 
> not too sure though how about HBase handles concurrent snapshot requests. Do 
> clients get an exception? Also we potentially could end up creating more 
> snapshots than we really need to. 
> 2) Do the checkAndPut for the UPGRADE_MUTEX in a different table (possibly 
> SYSTEM.SEQUENCE). This way the restored snapshot won't have the row. We would 
> need to delete the row from SYSTEM.SEQUENCE after the upgrade is done 
> (successfully or unsuccessfully).
> [~jamestaylor] - WDYT? 
> FYI, [~lhofhansl] - this is probably a blocker for 4.8.1



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