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https://issues.apache.org/jira/browse/PHOENIX-3534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16450233#comment-16450233
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Andrew Purtell commented on PHOENIX-3534:
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bq. Do we want to be able to rollback a release that contains this feature? If
so we will still have to propagate metadata changes from the base table to all
the child views and also ensure SYSTEM.CATALOG does not split.
Or is it possible to make an HBase level snapshot of the whole SYSTEM schema,
and then if there must be a rollback, we drop all of the upgraded SYSTEM tables
and restore from the snapshot? Of course views created inbetween snapshot and
rollback will be lost, but I think that is an acceptable tradeoff. Does this
then give you the freedom you need to make all of the necessary changes?
> 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: Thomas D'Silva
> Priority: Major
> Attachments: PHOENIX-3534-wip.patch
>
>
> 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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