Online table changes is a feature on TRUNK/.92 (dev-list, please comment).  
However, for .90 and before you need to disable.  Long story short, this has to 
do with the fact that the CFs metadata needs to be propagated to all the 
regions.   

For background, see:  http://hbase.apache.org/book.html#architecture 


________________________________________
From: Mikael Sitruk [[email protected]]
Sent: Thursday, October 27, 2011 3:19 AM
To: [email protected]
Subject: Adding a column family restriction

Hi

I have table in which I need to add column family. Nevertheless while trying
todo this via API or from shell this operation cannot be complete without
disabling the table first. From the business point of view i cannot affort
disabling the table.

So my questions are:
Why such restriction exist? I can understand for deleting a column family by
why for creating a new one?
Is there a plan to enable this in the future?
I have noticed that disabling/enabling table time is different from table to
table, what is the factor affecting the disable/enable time (number of
regions/volume of the table...)?

I also suggest to update the Javadoc to reflect this restriction on the
operation (currently no trace of this restriction in the javadoc)

Thanks
Regards,
Mikael.S

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