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From Mark Robson <mar...@gmail.com>
Subject Re: if cassandra isn't ideal for keep track of counts, how does digg count diggs?
Date Sun, 11 Apr 2010 10:30:57 GMT
Can we not implement counts by just storing all the deltas in a row, and
then summing them all up to acheive a count.

If a row ends up with too many deltas, a reader could just summarise the
deltas occasionally into a single value (in a way which avoids race
conditions, of course).

So you'd map

key => { uniqueid: delta1, uniqueid: delta2 }

Every column in Cassandra also has a timestamp, so your app can decide, when
it does a read, which deltas to summarise.

Mark

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