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From <Jeremy.Truel...@barclayscapital.com>
Subject RE: Subcolumn Indexing
Date Tue, 08 Feb 2011 20:23:18 GMT
Thanks, I just wanted to make sure I understand how it worked. Sounds like the additional mapping
vs super column method will work better for my purposes.

From: Benjamin Coverston [mailto:ben.coverston@datastax.com]
Sent: Tuesday, February 08, 2011 2:22 PM
To: user@cassandra.apache.org
Subject: Re: Subcolumn Indexing



Does this just mean the exhaustive list of the column names not all the values?
No, this means the entire supercolumn, names and values. When the client tries to access any
subcolumn in the supercolumn it has to read the entire supercolumn.

So if I have a super column that has a map of keys that only contain two columns max each
this shouldn't really be a performance concern correct? This becomes an issue when you have
lots of subcolumns if I'm reading this correctly? I'm looking at using the super column as
a good way to cluster data, say I was storing home addresses I might use the zipcode as the
super column if I cared mostly about accessing data by logical area for instance. Thanks for
the help.
That is one way to logically group the values, but I think that a simpler solution may be
to store the home address as a single row in a column family, then use a dynamic column family
to store references to those addresses per zip code.



jt
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