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https://issues.apache.org/jira/browse/PHOENIX-4579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16433716#comment-16433716
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ASF GitHub Bot commented on PHOENIX-4579:
-----------------------------------------

Github user ChinmaySKulkarni commented on the issue:

    https://github.com/apache/phoenix/pull/295
  
    @JamesRTaylor addressed review comments on 
ensureSystemTablesMigratedToSystemNamespace. Basically, now we return an 
UpgradeRequiredException even in the case that we need to migrate SYSTEM tables 
to the SYSTEM namespace. Just doing that was not sufficient since we would have 
to run 'EXECUTE UPGRADE' once for the migration and once for the upgrade (if 
required). 
    
    So, to avoid this, I am storing the SYSCAT timestamp as part of the 
UpgradeRequiredException and I have separated the SYSCAT schema upgrade code to 
another method. Now we only acquire the SYSMUTEX lock once (1. if we need to 
just perform an upgrade OR 2. if we need to migrate SYSTEM tables to the SYSTEM 
namespace and/or also perform an upgrade). 
    Added a test for this as well. Please let me know what you think about this 
approach. Thanks!


> Add a config to conditionally create Phoenix meta tables on first client 
> connection
> -----------------------------------------------------------------------------------
>
>                 Key: PHOENIX-4579
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4579
>             Project: Phoenix
>          Issue Type: New Feature
>            Reporter: Mujtaba Chohan
>            Assignee: Chinmay Kulkarni
>            Priority: Major
>         Attachments: PHOENIX-4579.patch
>
>
> Currently we create/modify Phoenix meta tables on first client connection. 
> Adding a property to make it configurable (with default true as it is 
> currently implemented).
> With this property set to false, it will avoid lockstep upgrade requirement 
> for all clients when changing meta properties using PHOENIX-4575 as this 
> property can be flipped back on once all the clients are upgraded.



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