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From Stefan Kaufmann <sta...@gmail.com>
Subject Using Cassandra for storing measurement data
Date Tue, 03 Aug 2010 07:21:29 GMT
Dear Cassandra Users,

I'm quite new to Cassandra and I'm still trying to figure out, if I'm
on the right path for my requirements.
I like to explain my Cassandra design and hope to receive feedback, if
this would work.

I like to use Cassandra to store measurement data from several
devices. Each device every minute - so there will be about 500 000
Entries per device every year.
Following data has to be stored:
 - device ID
 - measurement Time (of course different to the Cassandra time-stamp)
 - measurement value

Later, the data should be charted - so I need to select time-ranges
from a device.



My solution for is currently a super-column:
{
    name: "device1",
    value: {
        // measurement timestamps..
        1280819205: {name: "value", value: "10", timestamp: 123456789},
        1280819305: {name: "value", value: "15", timestamp: 123456789},
        1280819405: {name: "value", value: "10", timestamp: 123456789},
        //there will be millions of entries
    }
    name: "device2",
    value: {
        // measurement timestamps..
        1280819205: {name: "value", value: "20", timestamp: 123456789},
        1280819305: {name: "value", value: "15", timestamp: 123456789},
        1280819405: {name: "value", value: "20", timestamp: 123456789},
         //there will be millions of entries
    }
}

My questions:
My main concern is the huge amount of subcolumns I'm using. All the
examples of Cassandra in the web I saw, used those to store only a few
columns (like a user profile).
So would this work with millions of entries?

For my range-selections - I think I need the OrderPreservingPartitioner. Right?

Are there alternative designs? Maybe one without a Super-column? I
can't think of one..

I'm looking forward to some answers,
Thanks in advance,
Stefan

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