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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-3534) Support multi region SYSTEM.CATALOG table
Date Wed, 05 Apr 2017 23:47:41 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-3534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15958045#comment-15958045
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James Taylor commented on PHOENIX-3534:
---------------------------------------

Sorry, but I thought of another regression that the new scheme will cause. We currently use
Phoenix queries for our DatabaseMetaData.getColumns() implementation (see PhoenixDatabaseMetaData).
We'll need to do something fancier now with multiple queries for a view to get all of its
columns. Might be easier to make one query to get all the tables, and then go through our
client-side cache, faulting in any tables as necessary, driving this from our PTable instead.
This work could potentially be done in a separate JIRA, but some tests would need to be ignored
in the meantime.

> Support multi region SYSTEM.CATALOG table
> -----------------------------------------
>
>                 Key: PHOENIX-3534
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-3534
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: James Taylor
>            Assignee: churro morales
>
> Currently Phoenix requires that the SYSTEM.CATALOG table is single region based on the
server-side row locks being held for operations that impact a table and all of it's views.
For example, adding/removing a column from a base table pushes this change to all views.
> As an alternative to making the SYSTEM.CATALOG transactional (PHOENIX-2431), when a new
table is created we can do a lazy cleanup  of any rows that may be left over from a failed
DDL call (kudos to [~lhofhansl] for coming up with this idea). To implement this efficiently,
we'd need to also do PHOENIX-2051 so that we can efficiently find derived views.
> The implementation would rely on an optimistic concurrency model based on checking our
sequence numbers for each table/view before/after updating. Each table/view row would be individually
locked for their change (metadata for a view or table cannot span regions due to our split
policy), with the sequence number being incremented under lock and then returned to the client.



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