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From Ted Zlatanov <...@lifelogs.com>
Subject Re: why have ColumnFamilies?
Date Wed, 03 Mar 2010 14:32:05 GMT
On Wed, 3 Mar 2010 15:21:42 +0100 Alexandre Conrad <alexandre.conrad@gmail.com> wrote:


AC> 2010/3/3 Ted Zlatanov <tzz@lifelogs.com>:
KeySpace-> Row->ColumnFamily->Column[name, value]
>> (a two-level map)
>> 
KeySpace-> Row->SuperColumnFamily->SuperColumn[name]->Column[name, value]
>> (a three-level map)

AC> Thanks for the explanation. So this means that entities under
AC> SuperColumnFamily can only be SuperColumns and ColumnFamilies can only
AC> hold Columns.

AC> I guess the term SuperColumnFamily (which I haven't seen documented)
AC> is used when you want to implicitly say that SuperColumns are used
AC> beneath.

Sorry for the confusion.  I'm using SuperColumnFamily as a shortcut to
say "ColumnFamily of type 'Super'" which is what you'll find in the
configuration.

Your diagram was not incorrect.  It shows both Columns and SuperColumns
under the same family which can't happen in practice but logically do
live under the same branch.  So it's sort of correct but confusing :)

Ted


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