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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Cassandra range scans
Date Mon, 22 Feb 2010 20:34:56 GMT
On Mon, Feb 22, 2010 at 2:23 PM,  <Jeremey.Barrett@nokia.com> wrote:
>> You could use supercolumns here too (where the supercolumn name is the
>> thing type).  If you always want to retrieve all things of type A at a
>> time per user, then that is a more natural fit.  (Otherwise, the lack
>> of subcolumn indexing could be a performance gotcha for you:
>> http://issues.apache.org/jira/browse/CASSANDRA-598).
>
> Would you say the supercolumn approach is faster than scanning rows? Any particular advantages
or disadvantages to writing to a bunch of supercolumns at once (e.g. in one user row), vs.
writing to a bunch of rows at once (with the same key prefix, i.e. close together in an order-preserved
store)?

Depends.  What 598 says is that whenever you want to read any
subcolumns from a supercolumn, it has to deserialize all the
subcolumns.

So if you were going to ask for all of them anyway, no big deal.  But
if you just want a relatively small number, it will be non-negligible.

-Jonathan

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