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.