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From Doug Meil <doug.m...@explorysmedical.com>
Subject RE: Adding a column family restriction
Date Thu, 27 Oct 2011 13:34:06 GMT
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 [mikael.sitruk@gmail.com]
Sent: Thursday, October 27, 2011 3:19 AM
To: dev@hbase.apache.org
Subject: Adding a column family restriction


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)


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